EP1655540A1 - Control System Limiting Refuse Flow - Google Patents

Abstract

The method involves adapting a steam output setpoint starting from a waste weight applied to a charging system of the waste incineration plant and a preset maximum waste throughput, such that an economically appropriate operation is possible within a defined overload region. Independent claims are also included for the following: (A) a waste throughput limiting control device; and (B) a waste incineration plant.

Description

The invention relates to a waste-throughput limiting control for a fire power control of a waste incineration plant according to claim 1 and a method for operating a waste-throughput limiting control according to claim 11.

Waste incineration plants can use a heat output from waste incineration to convert it into electrical energy. For this purpose, the heat of combustion is coupled via heat exchangers with steam generators in steam boilers. The generated steam is directed via a steam distributor to a steam turbine where it serves its drive. As a measure of the steam power produced is generally a steam mass flow in [kg / s] indicated.

For the provision of a constant electric power by the steam turbine, it is again advantageous to keep the heat and the steam power constant. Calorific value fluctuations of the waste, due to a varying material composition, different porosity or pieceiness and a changing water content, must be compensated for this purpose by technical measures. These technical measures include an adjustment of the waste throughput.

A method for operating a waste incineration plant is known, for example, from EP-B-0499976. In this case, the garbage supply and the primary air supply by means of a uniform generation of heat quantity influenced in the same direction cascade control. The generated amount of steam is detected and serves as the main controlled variable. Strong changes in the quality of the waste and thus the calorific value, which require a change in the operating parameters in the opposite sense, are adequately compensated by this fire performance control accordingly.

Such a requirement occurs, for example, when moist waste - ie waste with a greatly reduced calorific value - is supplied to the combustion chamber. In the same direction increase the waste throughput, this can lead to a more incomplete combustion, the heat output is not adequately increased. In extreme cases, it can even come to extinguishing the fire.

In WO-A-01/25691 a method for waste incineration is described in which this circumstance is taken into account. For this purpose, starting from two controlled variables, the generated steam power and the oxygen content in the combustion chamber, the manipulated variables waste throughput and air supply to the combustion chamber are influenced. The regulation is carried out in such a way that the waste throughput or the air supply is reduced by a protective element when a predetermined maximum value is exceeded by at least one of the controlled variables.

Since the waste throughput in this process is detected indirectly via the steam power generated, in practice there may be discrepancies between this indirectly detected and the actual waste throughput. In addition, the indirectly recorded waste throughput is a quasi-current instantaneous value. In terms of the whole Dwell time of the waste in the supply and transport through the combustion chamber, which is in the order of 2 h, requires the indirect detection of the quasi-current instantaneous value a strong time-delayed reaction possibility with respect to the loading of the feed system.

Object of the present invention is therefore to provide a control unit for a fire power control of a waste incineration plant, which detects the actual waste throughput and thus the feed state and an ongoing, not operationally undesirable overload operation of the waste incineration plant is avoided.

The object is achieved by a waste throughput limiting control for a downstream combustion control of a waste incineration plant according to claim 1 and a method for operating a waste flow limiting control according to claim 11.

The inventive waste throughput limiting control has an averaging unit, a waste throughput limiting controller and a minimum unit. Starting from at least two input signals, a waste weight applied to a feed system of the waste incineration plant and a predetermined maximum waste throughput, the waste flow limiting control generates an output signal for a steam output setpoint for further processing in a downstream firing power control. The steam power setpoint is adjusted in such a way that at a determined depending on the weight of the garbage averaged waste throughput, which is greater than one of Maximum waste throughput dependent limit value, the Dartpfleistungssollwert is substantially reduced. As a result, the downstream combustion control will reduce waste throughput.

By such a regulation of the steam power setpoint as a reference variable for the downstream fire power control within the specified work area economic operation at the predetermined operating point ensures a temporally limited, economically reasonable and plant technology acceptable operation in the overload range and allows long-lasting overload by an unimpeded increase in the refuse in the Combustion of low-calorific waste efficiently prevented.

Fig. 1

ein Feuerungsdiagramm mit einem Arbeitsbereich und einem tolerierbarem Überlastbereich;

Fig. 2

ein Blockschaltbild einer Mülldurchsatz-Begrenzungsregelung (MBR) ;

Fig. 3

ein Diagramm mit einer zeitlichen Abfolge von Müllgewichten und einer Faltungsfunktion zur Bestimmung eines gemittelten Mülldurchsatzes;

Fig. 4

ein Blockschaltbild eines Mülldurchsatz-Begrenzungsreglers; und

Fig. 5

ein Diagramm, welches die Abhängigkeit eines Ausgangssignals des Mülldurchsatz-Begrenzungsreglers (MBr) vom Mülldurchsatz unter Einbezug eines Totbandes darstellt.

Advantageous embodiments of the invention will be described with reference to the following figures. The figures show in detail:

Fig. 1

a firing diagram with a working range and a tolerable overload range;

Fig. 2

a block diagram of a waste flow rate control (MBR);

Fig. 3

a diagram with a time sequence of waste weights and a convolution function for determining an average waste throughput;

Fig. 4

a block diagram of a waste flow limiting controller; and

Fig. 5

a diagram showing the dependence of an output signal of the waste throughput limiting controller (MBr) of the waste throughput with the inclusion of a dead band.

A firing diagram 10, as shown in Fig. 1, forms the basis for the design of a waste incineration plant. The heat output PW generated in the combustion process is represented in the firing diagram 10 as a function of the waste throughput MD. As parameters, straight lines of calorific values H0, H1, H2 of different waste qualities continue to be entered therein. A hexagonal area surrounds a work area 12 specified for the waste incineration plant, which includes all steady state conditions guaranteed by the manufacturer.

The working area 12 is limited by straight lines of a low calorific value H0 and a high calorific value H2, a minimum heat output 14 and maximum heat output 16 and a minimum waste throughput 18 and a maximum waste throughput 20. The heat output PW and the waste throughput MD of a desired operating point in the work area 12 fluctuate due to an inhomogeneous waste quality and due to a discontinuous loading of a feed system. In particular, at operating points that lie on the straight line of the maximum heat output 16 and the maximum waste throughput 20, these fluctuations can lead to overload conditions. Short-term overload conditions in the range of minutes usually do not lead to damage for the waste incineration plant. On the other hand, prolonged overload conditions are to be avoided in order to avoid after-effects, such as to avoid material fatigue, damming in the feeding system, unstable fire situation or exceeding of legal regulations.

Along the straight line of the maximum heat output 16, prolonged overload conditions can be effectively prevented by the above-mentioned fire power control FLR. In the overload region 22 following the straight lines of the maximum waste throughput 20, which is hatched in the firing diagram 10, the waste throughput limiting control MBR described below intervenes in order to prevent longer-lasting overload conditions. The waste-rate limiting control MBR occurs in the sense of a cascade control as a master controller for the reference variable steam setpoint DS of a downstream fire power control FLR, for example, according to EP-B-0499976 on.

FIG. 2 shows a block diagram of a waste throughput limiting control MBR. The material entry, that is the loading of waste, takes place with the aid of a gripper 24 of a crane system. The waste is discharged into a hopper, not shown, a hopper and loaded in this way, also not shown dispensing system. With the aid of a weight measuring cell GM, a pick-up weight MG picked up by the gripper 24 is determined and transmitted via an electrical signal line to the waste-throughput limiting control MBR. The detection of the garbage weights MG allows a detailed knowledge and analysis of the momentary state of the loading system (loading condition) and allows a targeted intervention to adapt the loading condition with changing garbage composition. In addition, through this Knowledge of the feed state and including a current steam power value extrapolation of future positions of the operating point and thus future operating conditions possible.

The waste throughput limiting control MBR is delimited by a dashed line in FIG. 2 and, in this preferred embodiment, comprises the following units: an averaging unit ME, a waste flow rate limiter MBr and a minimum unit MIN. The units ME, MBr, MIN are hardware and / or software implemented in this embodiment by means of electronic components. Alternatively, however, the units ME, MBr, MIN can also be realized by means of pneumatic components.

The averaging unit ME receives as input signal the garbage weights MG of each filled into the hopper garbage. The averaging unit ME determines therefrom over averaging period of 1 h to 5 h, preferably 3.5 h, a moving average of the garbage weights MG, divides this moving average by the averaging period and thereby generates an average garbage throughput gMD. In the present embodiment, the garbage weights MG are weighted with the folding function 26 shown in dashed lines in FIG.

In the diagram of FIG. 3, exemplary waste weights MG are shown as a function of time t in the form of bars applied with discrete time intervals. The averaging period ranges from -3.5 h to 0 h, which is 3.5 h. The plotted in Fig. 3 convolution function 26 has a steadily rising from the time 0 h, leading edge in time 28 and a steady from the time - 3 h falling, trailing edge 30 on. Between the leading and trailing edge 28, 30, the folding function 26 is at least almost constant. The averaging period can, of course, be adjusted to specific requirements. Thus, in practice, for example, it proves useful to form a further moving average value over 8 hours, which can be included in the control or is made available to a user as additional information. Like the averaging period, of course, the convolution function 26 can also be adapted to specific circumstances.

The calculation of a moving time average in time space corresponds to a filtering in frequency space. Therefore, the averaging unit ME described above is equivalent to a low-pass filter and can be physically replaced by such a low-pass filter. According to the adaptation of the convolution function 26 in the averaging unit ME, various parameters can also be adapted to the specific circumstances in the case of a low-pass filter. In the sense of a low-pass filter, the average garbage throughput gMD represents a smoothing of the garbage weights MG discretely filled into the hopper.

As input signal to the averaging unit ME downstream waste-rate limiting controller MBr, a so-called deadband TB is supplied in addition to the averaged waste throughput gMD. From the two input values gMD, TB, the waste-throughput limiting controller MBr determines a regulated steam power setpoint value DSr. A detailed description of the structure and function of the waste throughput limiting controller MBr is provided in connection with FIG. 4.

The minimum unit MIN following the signal flow to the waste-throughput limiting controller MBr receives, in addition to the regulated steam power setpoint value DSr, a steam power setpoint DSh determined manually by the operator and a calculated steam power setpoint DSb. The calculated steam power setpoint value DSb is determined in a steam power calculation unit DLB from at least one calorific value HWh to be entered by the operator on the basis of model calculations. The minimum unit MIN determines the smallest of the three input signals DSr, DSh, DSb and forwards this output signal of the waste-throughput limiting control MBR as a steam power setpoint DS to the downstream fire power control FLR. The fire power control FLR then generates corresponding control values, which influences the loading of the charging system via the gripper 24.

FIG. 4 shows a detailed block diagram of the waste throughput limiting controller MBr. In addition to the input signals already mentioned in connection with FIG. 2, the averaged garbage throughput gMD and the deadband TB, the garbage throughput limiting controller MBr has three further input signals not shown in the overview representation: a maximum garbage throughput MDmax, a scaling factor SF and an on / Off switch signal I / O.

In the signal flow direction, a differential waste throughput DMD is first determined from the difference between the averaged waste throughput gMD and the maximum waste throughput MDmax in a differential element DG. The differential waste throughput DMD is used together with the deadband TB, as an input signal Deadband adapter TBA supplied.

The function of the dead band adapter TBA will now be explained in connection with FIG. The diagram in FIG. 5 shows an output signal tDMD of the deadband adaptation element TBA as a function of the differential waste throughput DMD. The dead band adapter TBA outputs at a negative differential throughput DMD, which is the case when the average waste throughput gMD is less than the maximum waste throughput MDmax (gMD <MDmax), the differential throughput DMD (tDMD = DMD) at its output and thus to a downstream PI Controller PI-R continues. If the differential waste throughput DMD now reaches the value zero and exceeds the zero value up to a value specified by the deadband TB (0 <= DMD <= TB), in the case shown by 5% or 0.05, the output value becomes tDMD of the dead band adapter TBA is kept at zero (tDMD = 0). This ensures that within the interval [0..TB] the PI controller PI-R does not react substantially. Smaller fluctuations in the averaged garbage throughput gMD on the order of the dead band TB, which occur at the limit of the maximum garbage throughput 20, are suppressed or smoothed in this way. This leads to a calmer course of the output signal DS of the waste flow rate control MBR and allows the overload operation in the hatched in Fig. 1 overload range 22 of the Feuerungsdiagramms 10th

If the difference in throughput DMD (DMD> TB) increases further beyond the value of the deadband TB, the output signal tDMD = DMD-TB is lowered by the amount of the deadband TB. For comparison, a dash-dotted line 32 in the diagram in Fig. 5 along the Function tDMD = DMD entered. Reduces the average waste throughput gMD and thus also the differential waste throughput DMD again, the output signal tDMD passes through the stepped and in Fig. 5 consistently thick registered line of the transfer function 34 of the deadband adapter TBA in the reverse direction.

This design of the deadband adapter TBA ensures that the waste incineration plant is driven close to the maximum waste throughput 20, MDmax and thus operated economically, while at the same time overload conditions in a given mass are tolerated.

The output value tDMD is fed to the PI controller PI-R of known structure and function. A proportional coefficient and a reset time can be set as parameters of the PI controller PI-R but are not separately listed in FIG. 4 as input signals. The input signal tDMD is treated by the PI controller PI-R as a control deviation that is minimized according to the selected parameters. Essentially, for this purpose, the PI controller increases an output signal ds at a negative control deviation, that is, as long as the average waste throughput gMD is less than the maximum waste throughput MDmax, and reduces the output signal as soon as the control deviation has a positive sign, so the average waste throughput gMD minus the deadband TB exceeds the maximum waste throughput MDmax.

As an alternative to the described embodiment with a PI controller, it is of course also possible to use a PID controller or a fuzzy controller.

The output signal ds of the PI controller PI-R is through Multiplication with the scaling factor SF at a multiplier P in the regulated steam setpoint DSr converted and fed to the subsequent minimum unit MIN.

The further input signal I / O makes it possible to switch on or off the automatic operation of the waste-throughput limiting control MBR with the waste-throughput limiting controller MBr.

• 1. Der gemittelte Mülldurchsatz gMD liegt unterhalb des maximalen Mülldurchsatzes 20,MDmax, also im Arbeitsbereich 12. Das Differenzglied DG des Mülldurchsatz-Begrenzungsreglers Mbr liefert entsprechend ein negatives Eingangssignal DMD < 0 an die Totbandanpassungseinheit TBA, welche aufgrund ihrer oben beschriebenen Übertragungsfunktion 34 den Wert des Differenzmülldurchsatzes DMD an den PI-Regler PI-R weitergibt. Auf die entsprechend negative Regelabweichung reagiert der PI-Regler PI-R (unter Vernachlässigung seines Zeitverhaltens) mit einer Erhöhung seines Ausgangssignals ds. Nach der Skalierung des Ausgangssignals ds im Multiplikationsglied P wird der Dampfleistungssollwert DSr im nachfolgenden Minimumglied MIN ausgewertet. Ist der so bestimmte Dampfleistungssollwert DSr kleiner als der handeingestellte oder berechnete Dampfleistungssollwert DSh,DSb, so wird dieser als der aktuelle Führungswert an die Feuerleistungsregelung FLR weitergeleitet. Dieser Regelungsablauf wird solange den Dampfleistungssollwert DS erhöhen, bis das Minimumeinheit MIN einen geänderten handeingestellten oder berechneten Dampfleistungssollwert DSh, DSb als Minimum auswählt. Durch die Feüerleistungsregelung FLR kann die Müllzufuhr auf diese Weise weiter erhöht werden und ein wirtschaftlicher Betrieb am vorbestimmten Arbeitspunkt ist sichergestellt.
• 2. Der gemittelte Mülldurchsatz gMD liegt oberhalb des maximalen Mülldurchsatzes 20, MDmax, ist aber kleiner als die Summe aus dem maximale Mülldurchsatz MDmax und dem Totband TB. Der Arbeitspunkt im Feuerungsdiagramm 10 liegt also im tolerierbaren Überlastbereich 22. Das Differenzglied DG des Mülldurchsatz-Begrenzungsreglers MBr liefert entsprechend ein positives Eingangssignal DMD kleiner gleich dem Totband TB an die Totbandanpassungseinheit TBA. Gemäss seiner Übertragungsfunktion 34 gibt er den Wert Null an den PI-Regler PI-R weiter. Auf die Regelabweichung von Null reagiert der PI-Regler (unter Vernachlässigung seines Zeitverhaltens) im Wesentlichen derart, dass er unverändert den letzten Ausgabewert des Ausgangssignals ds vor Erreichung dieses "Gleichgewichtszustandes" beibehält. Nach der Skalierung des Ausgabesignals ds im Multiplikationsglied P, wird dieser so bestimmte Dampfleistungssollwert DSr im nachfolgenden Minimumeinheit MIN ausgewertet. Haben sich seit der letzten Veränderung des geregelten Dampfleistungssollwertes DSr der handeingestellte oder berechnete Dampfleistungssollwert DSh, DSb ebenfalls nicht geändert, so bleibt der an die Feuerleistungsregelung FLR weitergeleitete Dampfleistungssollwert DS unverändert. Auf diese Weise wird ein wirtschaftlich sinnvoller und anlagentechnisch vertretbarer (begrenzter) Betrieb im Überlastbereich gewährleistet.
• 3. Der gemittelte Mülldurchsatz gMD ist grösser als die Summe aus dem maximalen Mülldurchsatz 20, MDmax und zuzüglich des Totbandes TB, der Arbeitspunkt liegt also ausserhalb des Arbeitsbereiches 12 und des tolerierbaren Überlastbereichs 22. Das Differenzglied DG des Mülldurchsatz-Begrenzungsreglers MBr liefert ein negatives Eingangssignal DMD an die Totbandanpassungseinheit TBA, welche unter Berücksichtigung des Totbandes TB einen positiven Wert, der grösser ist als Null an den PI-Regler PI-R weitergibt. Auf die entsprechend positive Regelabweichung reagiert der PI-Regler PI-R (unter Vernachlässigung seines Zeitverhaltens) mit einer Verringerung seines Ausgabesignals ds. Nach der Skalierung des Ausgabesignals ds im Multiplikationsglied P, wird der so bestimmte geregelte Dampfleistungssollwert DSr in der nachfolgenden Minimumeinheit MIN ausgewertet. Unter der Annahme, dass der handeingestellte und berechnete Dampfleistungssollwert DSh, DSb seit der letzten Änderung des geregelten Dampfleistungssollwertes DSr nicht verändert wurde, leitet nun die Minimumeinheit MIN den verringerten geregelten Dampfleistungssollwert DSr als neuen aktuellen Dampfleistungssollwert DS an die Feuerleistungsregelung FLR weiter. Durch diese Verringerung des Dampfleistungssollwertes DS wird eine weitere Erhöhung der Müllzufuhr durch die bestehende Feuerleistungsregelung FLR effizient verhindert.

In the following, the function of the MBR is described on the basis of three essential situation scenarios:

• 1. The averaged garbage throughput gMD is below the maximum garbage throughput 20, MDmax, ie in the working area 12. The difference element DG of the garbage throughput limiting controller Mbr accordingly supplies a negative input signal DMD <0 to the deadband adjusting unit TBA, which due to their transfer function 34 described above, the value of differential refuse throughput DMD to the PI controller PI-R. In response to the correspondingly negative control deviation, the PI controller PI-R (neglecting its time behavior) reacts with an increase in its output signal ds. After the scaling of the output signal ds in the multiplication element P, the steam power setpoint DSr is evaluated in the following minimum element MIN. If the steam power setpoint DSr thus determined is smaller than the manually set or calculated steam power setpoint value DSh, DSb, then this is forwarded as the current control value to the fire power control FLR. This control procedure will continue to increase the steam power setpoint DS until the minimum unit MIN has changed the manual set or calculated steam output setpoint DSh, DSb as minimum selects. By Feüerleistungsregelung FLR the refuse can be further increased in this way and economic operation at the predetermined operating point is ensured.
• 2. The average waste throughput gMD is above the maximum waste throughput 20, MDmax, but is less than the sum of the maximum waste throughput MDmax and the deadband TB. The operating point in the firing diagram 10 thus lies within the tolerable overload range 22. The differential element DG of the waste-throughput limiting controller MBr correspondingly delivers a positive input signal DMD smaller than the deadband TB to the deadband adjusting unit TBA. According to its transfer function 34, it passes the value zero to the PI controller PI-R. In response to the control deviation of zero, the PI controller (neglecting its timing) essentially reacts in such a way that it still retains the last output value of the output signal ds before reaching this "equilibrium state". After the scaling of the output signal ds in the multiplication element P, this so determined steam power setpoint DSr is evaluated in the subsequent minimum unit MIN. If the manually set or calculated steam power setpoint value DSh, DSb have not changed since the last change of the regulated steam power setpoint value DSr, the steam power setpoint value DS forwarded to the fire power control FLR also remains unchanged. In this way an economically reasonable and plant technically acceptable (limited) operation in the overload area is guaranteed.
• 3. The average waste throughput gMD is greater than that Sum of the maximum waste throughput 20, MDmax and plus the dead band TB, the operating point is thus outside the working range 12 and the tolerable overload range 22. The difference element DG of the waste flow limiting controller MBr provides a negative input signal DMD to the dead band adjustment unit TBA, which takes into account the Deadband TB a positive value that is greater than zero to the PI controller PI-R passes. In response to the correspondingly positive control deviation, the PI controller PI-R (neglecting its time behavior) reacts with a reduction of its output signal ds. After the scaling of the output signal ds in the multiplication element P, the regulated steam power setpoint DSr thus determined is evaluated in the subsequent minimum unit MIN. Assuming that the manual set and calculated steam duty DSh, DSb has not been changed since the last change in the regulated steam duty DSr, the minimum unit MIN now forwards the reduced regulated steam duty DSr as the new actual steam duty DS to the fire power control FLR. By this reduction of the steam power setpoint DS, a further increase of the waste feed is effectively prevented by the existing fire power control FLR.

The method for operating the waste throughput limiting control MBR described above comprises at least the step that, starting from at least two input signals, namely the refuse weight MG and the predetermined maximum refuse throughput MDmax, an output signal Dampfleistungssollwert DS for further processing in the Feuerleistungsregelung FLR is generated such that at depending on Mine weight MG determined average garbage throughput gMD, which is greater than a maximum dependent on the maximum waste throughput MDmax limit, the steam power setpoint DS is reduced in order to prevent a continuous overload operation of the incinerator. The method preferably includes a further input signal, namely a deadband TB, such that it is greater than the maximum waste throughput MDmax and less than or equal to the limit value resulting from the sum of the maximum values at an average waste throughput gMD Garbage throughput MDmax and the deadband TB results, the steam power setpoint DS (with unchanged manually set and calculated steam power setpoint DSh, DSb) remains constant. The averaged garbage throughput gMD is determined in a previous process step as a moving time average from the garbage weights MG in the averaging unit ME.

Claims (13)

Waste rate limiting control for a downstream combustion control (FLR) of a waste incineration plant in which a long-term overload due to an unimpeded increase in refuse incineration in the combustion of low calorific value waste (H0) is prevented by adjusting the vapor power target value (DS), characterized in that the Waste throughput limit control (MBR) is equipped with a waste flow rate regulator (Mbr) and an averaging unit (ME) and based on at least two input signals, namely a waste weight (MG) applied to a feed system of the waste incineration plant and a predetermined maximum waste throughput (MDmax), the steam power setpoint (DS) for further processing in the fire power control (FLR) is adapted in such a way that at an average garbage throughput (gMD) determined as a function of the garbage weight (MG) that is greater than one of the maximum garbage throughput ( MDmax) dependent limit value, the steam power setpoint (DS) is reduced. Waste throughput limiting control according to claim 1, characterized in that the waste throughput limiting controller (MBr) has a proportional integral (PI) - controller (PI-R). Waste rate limiting control according to claim 1 or 2, characterized in that the waste throughput limiting controller (MBr) has a deadband adaptation unit (TBA) for processing a further input signal, namely a deadband (TB), whereby the steam power setpoint (DS) is determined so that it is greater than the maximum waste throughput (gMD) at an average MDmax) and less than or equal to the threshold resulting from the sum of the maximum waste throughput (MDmax) and deadband (TB) values, the steam power setpoint (DS) remains substantially constant. Waste rate limiting control according to claim 3, characterized in that the value of the dead band (TB) is 0% to 20%, preferably 5%. Garbage rate limiting control according to one of claims 1 to 4, characterized in that in the averaging unit (ME) the averaged garbage throughput (gMD) is determined as a sliding time average from the garbage weights (MG). Garbage rate limiting control according to one of claims 1 to 5, characterized in that in the averaging unit (ME) the averaged garbage throughput (gMD) is determined by a sliding time averaging with a weighting, at its temporally leading edge (28) slowly rising and on its trailing edge (30) slowly falling convolution function (26). Waste throughput limiting control according to claim 6, characterized in that the leading edge (28) of the folding function (26) over a period of 0.1 h to 2 h, preferably over a period of time increases linearly from 0.5 h, the folding function (26) between the leading and trailing flanks (26, 28) is at least almost constant and the trailing edge (28) of the folding function (26) over a period of 0.1 h to 2 h, preferably linearly over a period of 0.5 h. Waste throughput limiting control according to one of claims 5 to 7, characterized in that the sliding time averaging over a period of 1 h to 5 h, preferably extending over 3.5 h. Waste throughput limiting control according to one of claims 1 to 5, characterized in that the averaging unit (ME) is designed as a low-pass filter. The waste throughput limiting control according to any one of claims 1 to 9, characterized in that the waste flow rate control (MBR) has a minimum unit (MIN) which sets the steam power setpoint (DS) as the minimum of an output signal (DSr), manually set, provided by the waste flow rate limiter Steam power setpoint (DSh) and a calculated steam power setpoint (DSb) determined. A method of operating a waste flow limiting control for a downstream combustion power plant (FLR) of a waste incineration plant according to any one of claims 1 to 10, wherein a long-term overload due to an unimpeded increase in refuse incineration in the combustion of low calorific value waste (H0) by adjusting the Steam power set point (DS) is prevented, characterized in that starting from at least two input signals, namely applied to a feed system of the waste incineration plant garbage (MG) and a predetermined maximum waste throughput (MDmax), the steam power setpoint (DS) for further processing in the fire power control (FLR ) is adjusted such that at a determined in dependence on the weight of the garbage (MG) averaged garbage (gMD), which is greater than a maximum garbage throughput (MDmax) dependent limit, the steam power setpoint (DS) is reduced. Method for operating a waste-rate limiting control according to claim 11, characterized in that in a further method step, a further input signal, namely a dead band (TB) for determining the steam power setpoint (DS) is included such that it at an average waste throughput (gMD), which is greater than the maximum waste throughput (MDmax) and less than or equal to the limit resulting from the sum of the values of the maximum waste throughput (MDmax) and the deadband (TB), the steam power setpoint (DS) remains substantially constant. Method for operating a waste-rate limiting control according to claim 11 or 12, characterized in that in a further method step the averaged waste throughput (gMD) is determined as a moving time average from the garbage weights (MG).

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