EP1489355B1 - Method and Apparatus for Controlling the Heat Output of Incinerators - Google Patents

Abstract

The technique is for the control of the firing power of a solid fuel burner assembly, where the fuel is delivered to the start of a firing grate (1) to be poked and advanced for the ashes to drop away at the end. The control actions are taken from measured values for the vapor volume (MD), at least one gas type in the emissions and the temperature of the fuel at the firing zone (3), using given and variable weightings. The controls are applied to the fuel feed speed (WB) from the charging station to the firing grate, the grate movement speed (WRN), the fuel poking speed (WSN), together with the primary air volume (LPn), the secondary air volume (LSn) between the firing and after-burner (4) zones, the tertiary air volume (LT) at the side walls, and the primary air temperature (TPL). The weighting matrix follows a normal value of 10 taken values.

Description

The invention relates to a method and a device for controlling the fire performance of incinerators.

Such a method and an apparatus is known from DE OS 198 20 038 A1 known. This document proposes that to regulate the performance of the fire in adaptation to the steam power requirements influencing the warping and locomotion of the fuel in dependence on the combustion air permeability of Feuerungsrost and fuel bed is done to cope with the problems of different Brennbetthöhen. From this document, it is thus known to influence the task amount of the fuel in dependence of the combustion air permeability of Feuerungsrost and fuel bed.

The DE OS 39 04 272 A1 deals with an improvement of the combustion process on the grate and proposes for this purpose a detector device in the form of several thermographic or infrared cameras, which detects the corresponding good bed temperature radiation of individual grate zones and the individual grate zones separately adjustable adjusting devices for the supply of Primary air and / or for the speed of the fuel in the good bed by individual grate zones are assigned. From this document is thus known the regulation or control of the individual grate zones with respect to primary air supply and / or for the speed as a function of measured grate zone temperatures.

From the DE OS 42 20 149 A1 Finally, it is known to the combustion process by means of a so-called fuzzy logic to optimize. In this case, measured values are detected by the individual zones and the partial streams assigned to the individual zones are individually regulated according to the fuzzy logic as a function of a distribution of the measured values in terms of area. In particular, the transport speed of the fuel in the zones is regulated according to the fuzzy logic. It is thus also known from this document, inter alia, to detect the radiation emanating from the individual zones, and to regulate the combustion as a function of the areal distribution of the radiation.

EP 0 661 500 A discloses a method and a device for controlling the performance of the fire in which firing is abandoned at the beginning of a Feuerungsrostes, subjected to this on a locomotion and at the end of the Feuerungsrostes, the slag is discharged, the control of the fire performance is done in response to control variables. The controlled variables used are oxygen content and / or CO content in the exhaust gas, furnace temperature, fuel bed height, and / or dust concentration. The manipulated variables include the primary air quantity, the grate speed, the quenching speed and the secondary air quantity. A radar device allows a three-dimensional detection of the fuel distribution on the furnace grate. In addition, an infrared camera provides information about the combustion behavior of the fuel on the combustion grate.

The invention has for its object to optimize the fire control in incinerators, especially solid fuel combustion systems so that the formation of pollutants is reduced or prevented within the combustion process, the combustion conditions in the furnace should be continuously adjusted so that combustion-dependent emission loads can be influenced. An essential goal of the fire performance control is in addition to optimal primary measures for emission reduction a maximum, as constant as possible energy conversion.

This object is achieved by the method specified in claim 1 and the device specified in claim 11.

According to the inventive method or the device for controlling the fire performance of incinerators, especially solid fuel burning systems, abandoned in the kiln at the beginning of a firing grate, subjected to this a locomotion and locomotion and at the end of the firing grate the resulting slag is discharged, it is provided that the control of the fire performance with regard to a possible constant maintenance of the produced amount of steam on the one hand and with regard to the lowest possible emission of pollutants on the other hand, and a possible boiler-preserving or corrosion of the boiler pipes preventive operation as a function of at least three measured or from measured values derived control variables A, B, and C, wherein the controlled variable A is derived from the measured amount of steam, the controlled variable B at least one gas type of the emitted substances directly or indirectly, and the controlled variable C from at least one of the fuel bed or the firebox associated temperature and / or calorific value of the combustible material is derived, and the control of the manipulated variables as a function of at least three measured or derived from measurements controlled variables in a predetermined, variably adjustable weighting of these control variables takes place.

In accordance with the principle of the invention, provision is made in particular for the controlled variable B to reproduce the oxygen content of the emitted substances directly or indirectly. The measurement of the oxygen content O ₂ in the flue gas of the incinerator takes place by means of a gas detector installed at a suitable location preferably in the flue of the incinerator gas detector with which, among other types of gas, the oxygen content O _{2 of} the flue gas can be measured and processed as a controlled variable. Since the total amount of air is kept constant depending on the load, the average oxygen content of the flue gas is constant with constant heat release and constant fuel composition. The method according to the invention is based on the finding that the O ₂ signal corresponding to the oxygen content of the flue gas reacts the fastest to a change in the intensity of the fire. The oxygen content O ₂ in the flue gas is inversely proportional to the live steam mass flow and can thus be used as an early indicator for a changing steam signal.

The power and oxygen regulators thus affect both the feed and all rust zones. It is important that the oxygen regulator is negatively weighted. This is due to the fact that an O ₂ setpoint and actual value behave in opposite directions, ie inversely proportional to each other. A too low O ₂ content, ie actual value <setpoint value, cancels close a too high or increasing amount of steam. If the regulator were weighted positively, it would make the grate and the charge faster in this case, which would be wrong if the amount of steam was already too high or increasing anyway. For this reason, the O ₂ controller is negatively weighted, so if the O ₂ value is too low, the rust and feed (if weighted) slows down.

In a further advantageous embodiment of the invention, it is provided that the controlled variable C is determined from the firing position and / or the firing length of the firing bed, wherein the firing position is derived from one or more measured temperatures at the beginning of the grate or temperatures in the afterburning chamber, and the firing length one or more measured temperatures at the output end of the furnace grate is derived. From experiments it has emerged that the furnace temperatures are also suitable as substitute or additional measured variables for the vapor signal due to their short dead time. In order to obtain a representative value, the mean value can be formed from several temperatures and used for regulation. This average temperature value thus allows as a substitute measured value THu a conclusion on the Brennstoffheizwert Hu. If this temperature is particularly low, the firing position x moves in the direction of slag discharge, as in particular in Fig. 2 is shown in more detail. A pyrometer above the burnout zone indirectly measures the slag temperature. Falling temperatures indicate a shortening of the fire on the grate, rising temperatures on an extension. The correspondingly measured temperature value can thus also be used as a substitute measured variable T _I for the fire length I. It is now advantageous in a further development of the invention to be able to influence the firing position x as well as the fire length I by a variation of the transport speeds of the grate. Here, the regulation of the loading and transport speeds can be fully automated. In addition to the power controller of the manipulated variable y _F and the O ₂ controller with the manipulated variable y _O2 allows the invention in addition, a "calorific value controller" with the manipulated variable y _Hu and a "Feuerlagereger" with the manipulated variable y _I.

• die Beschickungsgeschwindigkeit, d.h. Geschwindigkeit, mit welcher der Brennstoff von der Beschickeinrichtung auf den Feuerungsrost aufgegeben wird,
• die Rost-Transportgeschwindigkeit, d.h. Geschwindigkeit, mit welcher das Brenngut über den Verbrennungsrost gefördert wird,
• die Rost-Schürgeschwindigkeit, d.h. Geschwindigkeit, mit welcher das Brenngut in den einzelnen Rostzonen geschürt wird, die an der jeweiligen Rostzone beaufschlagte Primärluftmenge, die im vorderen und hinteren Bereich des Feuerraumes vorherrschende Sekundärluftmenge,
• die im mittleren Bereich des Feuerraumes - soweit physikalisch vorhanden - vorherrschende Tertiärluftmenge, sowie die Primärlufttemperatur. , d.h. Temperatur im Feuerraum.

The control variables of the incinerator to be controlled include the following quantities:

• the feed rate, ie the rate at which the fuel is fed from the hopper to the grate,
• the rust transport speed, ie the speed with which the kiln is conveyed via the combustion grate,
• the speed of rusting, that is to say the speed at which the material to be burned in the individual grate zones is stoked, the quantity of primary air applied to the respective grate zone, the quantity of secondary air prevailing in the front and rear regions of the combustion chamber,
• the tertiary air quantity prevailing in the middle area of the firebox - as far as physically present - as well as the primary air temperature. ie temperature in the firebox.

A particular advantage of the invention consists in the fact that the fire power control can be set for different types of fuel, with a separate parameter set for the fire performance control is provided for each type of fuel, the method for controlling the fire power during operation of the combustion system to other types of fuel is switched or switched can be.

In a particularly advantageous and therefore preferred embodiment of the invention, the weighting of the controlled variables takes place in relation to the manipulated variables in the form of weighting factors, the quantity of which in particular according to the FIG. 3 present weighting matrix. In numerical terms, these weighting factors have, for example, the following values, each related to a standard value of 10: feed rate transport speed stoking Air volumes u. -distribution Primary air temperature Amount of steam ṁ _D 9 - 10 9 - 10 0 9 - 10 0 Oxygen O ₂ 7 - 9 7 - 9 9 - 10 5 - 7 0 Fire position T _Hu 0 2 - 4 0 4 - 6 9 - 10 Fire length T _I 0 7 - 9 0 3 - 5 0

The numerical values given are approximate and may vary depending on the type of plant used.

In an advantageous development of the invention, a fourth controlled variable D is provided which is derived from the layer thickness and / or the air permeability of the combustion material located on the firing grate. The measurement of the controlled variable D is preferably carried out by a pressure sensor. By measuring the controlled variable D in the Primärläftkanal the pressure can be measured, which is opposed to the primary air through the lying on the grate kiln. This makes it possible to draw conclusions about which type of material is on the grate (wet, heavy waste = high primary air pressure, bulky waste = low primary air pressure) and / or in which layer thickness this is present. Thus one can e.g. also detect if there is a seepage or similar perturbation on the side of the feed, and respond accordingly.

Other features, advantages and advantages of the invention will become apparent from the other dependent claims.

FIG. 1

eine schematisierte Schnittansicht der Verbrennungsanlage mit Darstellung der Stell- und Regelgrößen der Rostfeuerung;

FIG. 2

einen Längsschnitt durch eine schematisch dargestellte Verbrennungsanlage;

FIG. 3

eine schematische Darstellung des Feuerraumes mit drei unterschiedlichen Temperaturverteilungen;

FIG. 4

eine schematische Gewichtungsmatrix zur Darstellung eines Regelschemas in Abhängigkeit der Stell- und Regelgrößen der Verbrennungsanlage;

FIG. 5

Regelungsablauf unter Berücksichtigung der lastabhängigen Luftmengen und Primärluftverteilung sowie der gesteuerten Luftmengenverteilung; und

FIG. 6

eine schematische Darstellung des Verfahrens- und Regelungsablaufes unter Berücksichtigung der lastabhängigen Transportgeschwindigkeiten und Korrektur und Anpassung der Transportgeschwindigkeiten.

The invention will be explained in more detail below in conjunction with the drawing of an embodiment of an incinerator and with reference to operating results in connection with this incinerator. It shows:

FIG. 1

a schematic sectional view of the incinerator with representation of the control variables of the grate furnace;

FIG. 2

a longitudinal section through a schematically illustrated combustion system;

FIG. 3

a schematic representation of the furnace with three different temperature distributions;

FIG. 4

a schematic weighting matrix for representing a control scheme as a function of the manipulated and controlled variables of the incinerator;

FIG. 5

Control sequence taking into account the load-dependent air volumes and primary air distribution as well as the controlled air volume distribution; and

FIG. 6

a schematic representation of the process and control process taking into account the load-dependent transport speeds and correction and adjustment of the transport speeds.

In the FIG. 1 and 2 schematically illustrated combustion system comprises a Feuerungsrost 1, a charging device 2, a combustion chamber 3 with subsequent throttle cable 4, to which connect further throttle cables and the incinerator downstream units, in particular steam generation and emission control systems, which are not shown and explained in detail here.

The grate 1 comprises individually driven grate stages 5. Said drive makes it possible to adjust both the transport or conveying speed and the quenching speed. The firing grate has, in addition to the transport of the fuel 16 and the function to stoke the kiln. Below the firing grate divided subwind chambers 7.1 to 7.5 are provided both in the longitudinal direction and in the transverse direction, which are acted upon separately via individual lines 8.1 to 8.5 with primary air L̇ _P. At the end of the firing grate 1, the burned slag is discharged into a slag chute 10, from where the slag falls into a non-slag chaff.

The loading device 2 comprises a feed hopper 11, a feed chute 12, a feed table 13 and one or more juxtaposed and / or superimposed, optionally independently controllable feed piston 14, which slips down in the feed chute 12 via a garbage feed 15 feeder table 13 in the Push combustion chamber 3 onto the combustion grate 1.

About the feed of the fuel from the lower mouth of the hopper 11 is given evenly over the entire grate width. In the illustrated embodiment is a system with a discontinuous feed with a four-part Dosierstößel (top left, top right, bottom left, bottom right). Through a slow forward stroke and a fast return stroke of the furnace grate 1 can be quasi fed continuously.

The fuel 16 applied to the furnace grate 1 is pre-dried by the air coming from the underwinding zone 7.1 and heated and ignited by the radiation prevailing in the furnace 3 radiation. In the area of the underwinding zones 7.2 and 7.3, the main fire zone is located, while in the area of the underwinding zones 7.4 and 7.5 the forming slag burns out and then reaches the slag chute 10.

In schematic form, various actuators are in FIG. 1 and 2 indicated that serve to control various factors or devices to perform the desired control of the fire performance can. In this case, the adjusting devices for influencing the transport and speeding speeds wsn with 21, for the on and off frequency or for the speeds w _{B of} the feed piston with 23, and designated for the primary air quantities L _Pn with 24, which is able to each individual sub-wind chamber 7 to supply the required primary air quantities L̇ _Pn .

To determine the desired controlled variable, which corresponds to the first approximation of the free air outlet surface through the grate and the fuel bed, in each air supply line 8, an air flow meter 18 and in the underwinding chambers 7.1 and 7.2, a temperature sensor 17 and in the underwinding chamber 7.1 a pressure sensor 19 is provided while two further temperature sensors 20a and 20b are arranged in the combustion chamber 3 in order to be able to measure the temperatures at two different locations in the combustion chamber 3.

Hereinafter, with additional reference to the FIGS. 3 to 6 explains the inventive method, which is characterized in that the control of the fire performance in dependence on at least three measured or derived from measured values controlled variables A, B, and C, wherein the controlled variable A is derived from the measured amount of steam, the controlled variable B at least one Gas type of emitted substances directly or indirectly reproduces, and the controlled variable C derived from at least one of the fuel bed or the firebox associated temperature and / or calorific value of the fuel is, and the control of the manipulated variables as a function of at least three measured or derived from measurements controlled variables in a predetermined, variably adjustable weighting of these control variables.

One goal of optimal fire control is to reduce or prevent the formation of pollutants within the combustion process. For this purpose, the combustion conditions in the combustion chamber are continuously adjusted so that combustion-dependent emission loads can be influenced. These measures are of particular importance, as they do not displace the pollutants but can actually reduce or prevent their formation. These are therefore dynamic measures that intervene in the combustion process in terms of control technology. These measures are summarized under the term "combustion control". However, the historically coined term is misleading insofar as not only the fire performance, ie the steam production, is regulated by the fire power control, but in parallel and even superficially the combustion-dependent pollutants are minimized. Another key objective of the so-called "fire performance control" is, in addition to optimal primary measures for emission reduction, a maximum, as constant as possible energy conversion. The usually prevailing rule philosophy here consists in a fixation on a guaranteed nominal steam generation, i. to "dash" drive the incinerator under any time compliance with the set value.

Important for the basic principles of the invention is the measurement of the oxygen content O ₂ in the flue gas of the incinerator. For this purpose, a gas detector 25 is installed at a suitable location in the throttle cable 4, with which, inter alia, the oxygen content O _{2 of} the flue gas can be measured and processed further as a controlled variable.

Since the total amount of air is kept constant depending on the load, the average oxygen content of the flue gas is constant with constant heat release and constant fuel composition. In tests, it has now been found that the O ₂ signal reacts the fastest to a change in the fire intensity. The oxygen content O ₂ in the flue gas is inversely proportional to the live steam mass flow and can thus be used as an early indicator for a changing steam signal.

The power and oxygen regulators thus affect both the feed and all rust zones. It is important that the oxygen regulator is negatively weighted. This is due to the fact that a 02-Soll- u. Actual value in opposite directions - ie inversely proportional to each other. Too low an O ₂ content, ie actual value <set value, indicates an excessive or increasing steam quantity. If the regulator were weighted positively, it would make the grate and the charge faster in this case, which would be wrong if the amount of steam was already too high or increasing anyway. For this reason, the O ₂ controller is negatively weighted, so if the O ₂ value is too low, the rust and feed (if weighted) slows down.

The temperature sensor 20a measures the combustion chamber temperature in the area of the afterburning chamber, and the temperature sensor 20b measures the combustion chamber temperature in the area of the end of the rust in the combustion ceiling. The two temperature sensors 20a and 20b are, for example, radiation pyrometers ("cameras"), which are installed at suitable locations in the afterburner chamber or in the burnout ceiling at the grate end. The two radiation pyrometers 20a and 20b are intended to be able to draw conclusions about the calorific value of the current fuel and, if necessary, to react to it and to be able to initiate suitable countermeasures.

From experiments it has emerged that the furnace temperatures are also suitable as substitute or additional measured variables for the vapor signal due to their short dead time. In order to obtain a representative value, the mean value of both temperatures is formed and used for regulation. This average temperature value thus allows as a substitute measured variable T _Hu a conclusion on the Brennstoffheizwert H _u .

In the FIG. 3 These relationships are shown with reference to three schematically illustrated curves 1, 2 and 3 of the firing temperatures of the fuel as a function of the geometric size x ("fire length"). Curve 1 shows the normal temperature distribution. If the mean temperature value T _{Hu is} lower than a normal value, the curve maximum of the firing position x moves in the direction of slag discharge, as shown in curves 2 and 3 in FIG Fig. 3 is shown in more detail, wherein the curve 3 represents a particularly low average temperature T _Hu . The pyrometer 20b above the burnout zone indirectly measures the slag temperature. Falling temperatures TI indicate a shortening of the hearth on the grate towards the feed, increasing temperatures TI on an extension of the fire length towards slag discharge.

The camera 20b supplies a signal, which can thus also be used as a substitute measured variable TI for the fire length I. It now makes sense to be able to influence the firing position x and the firing length I by varying the transport speeds of the grate. Here, the regulation of the loading and transport speeds can be fully automated. In addition to the power controller of the manipulated variable y _F and the O ₂ controller with the manipulated variable Y _O2 , the invention also allows a "calorific value" with the manipulated variable Y _Hu and a "Feuerlagereger" with the manipulated variable Y _I.

Based on the schematic representations according to FIG. 4 . 5 and 6 Further details of the method according to the invention of the combustion control system are described, namely shows Fig. 4 a schematic weighting matrix of the control scheme as a function of the control variables of the incinerator with weighting factors, and the FIG. 5 and 6 schematically the regulatory processes, in FIG. 5 the load - dependent air volumes and the primary air distribution as well as the controlled air volume distribution, and in FIG. 6 the load-dependent transport speeds, as well as correction and adjustment of the transport speeds are taken into account.

All measured quantities are in an in Fig. 2 summarized by the reference numeral 26 shown measured value detection device, and the evaluation of the measured data and the actual control is done with a in Fig. 1 summarized by the reference numeral 27 designated evaluation and control circuit. This circuit 27 controls, inter alia, in the Fig. 5 and 6 designated PID controller (PID = proportional-integral-differential controller), and includes or controls other electronic circuit components for the operation of the incinerator, which in the Fig. 5 and 6 assigned magnitudes are assigned, but are not shown in detail explicitly. After the in the Fig. 5 and 6 A distinction is made between a controlled operation and a controlled operation of the incinerator, wherein between the two modes of operation via a switch 28 (FIG. Fig. 5 and 6 ) can be selected. In controlled operation, there is no control of the combustion system, this mode of forced control is used only in exceptional cases, for example, when starting the combustion system or in accidents. However, there is certainly a load-dependent automatic adjustment of the parameters. The more interesting and relevant to the invention operating mode is the "regulated operation".

On the input side, each PID controller has a connection w for the respective corresponding input variable as setpoint and a connection x for the corresponding actual value of the controlled variable, and supplies at the output in each case a manipulated variable value y to the evaluation and control circuit 27. This supplies, taking into account Correction factors K and, above all, taking into account the weighting factors G predetermined according to the invention, the corresponding control signals for regulating the air quantities L̇ (FIG. Fig. 5 ) or the loading, purging and transport speeds ẇ ( Fig. 6 ).

Ẇ_B

Beschickungsgeschwindigkeit (Geschwindigkeit, mit welcher der Brennstoff von der Beschickeinrichtung 2 auf den Feuerungsrost 1 aufgegeben wird)

Ẇ_Rn

Rost-Transportgeschwindigkeit (Geschwindigkeit, mit welcher das Brenngut durch die einzelnen Rostzonen R1 - R5 befördert wird)

ẇ_Sn

Rost-Schürgeschwindigkeit (Geschwindigkeit, mit welcher das Brenngut in den einzelnen Rostzonen R1...R5 geschürt wird)

L̇_ges

gesamte Verbrennungsluftmenge

L̇_Pn

Primärluftmengen (an der jeweiligen Rostzone R1 ... R5 beaufschlagte Primärluftmenge)

L̇_Sn

Sekundärluftmengen (in den vorderen und hinteren Ubergang des Feuerraums zur Nachbrennzone eingebrachte Luftmenge)

L̇_T

Tertiärluftmenge (in der linken und rechten Seitenwand des Feuerraumes eingebrachte luftmenge)

T_PL

Primärlufttemperatur

T_I

Temperatur Feuerlänge (Temperatur am ausgangsseitigen Ende des Feuerungsrostes)

T_Hu

Temperatur Heizwert (Temperatur am beschickungsseitigen Anfang des Verbrennungsrostes)

ṁ_D

Dampfmenge (Frischdampf-Massenstrom, Dampfmenge)

ṁ_D,soll

gewählte thermische Last, Solldampfmenge

ṁ_D,ist

Ist-Dampfmenge (gemessen)

O₂

Sauerstoffanteil (Sauerstoffgehalt im Rauchgas)

O_2,soll

Soll-Sauerstoffgehalt im Rauchgas

O_2,ist

Ist-Sauerstoffgehalt im Rauchgas

X_soll, Y_soll, Z_soll

weitere Sollgrößen

X_ist, Y_ist, Z_ist

weitere Ist-Größen

y_F

Stellgröße Festlastregler

y_O2

Stellgröße Sauerstoffgehalt

y_X, y_Y, y_Z

Stellgrößen für die Werte X, Y, Z

G_F

Gewichtungsfaktor Festlast

G_O2

Gewichtungsfaktor Sauerstoff

G_X, G_Y, G_Z

Gewichtungsfaktoren der Größen X, Y, Z

K_F

Korrekturfaktor Leistung

K_O2

Korrekturfaktor Sauerstoff

K_X, K_Y, K_Z

Korrekturfaktoren der weiteren Größen X, Y, Z

L̇_P(Z1)

Mengenstrom Primärluftrostzone 1

Ẇ_R1

Geschwindigkeit Rostzone 1
usw. entsprechend den verschiedenen Indizes für jede weitere Rostzone 2, 3, 4, und 5.

The in the figures (and related description), in particular in the Fig. 5 and 6 designated sizes have the following meaning:

Ẇ _B

Charging speed (speed at which the fuel is fed from the charging device 2 to the Feuerungsrost 1)

Ẇ _Rn

Grate transport speed (speed at which the firewood is transported through the individual grate zones R1 - R5)

ẇ _Sn

Grinding speed (speed with which the firing material in the individual grate zones R1 ... R5 is stoked)

L̇ _ges

total amount of combustion air

L̇ _Pn

Primary air quantities (primary air quantity applied to the respective grate zone R1 ... R5)

L̇ _Sn

Secondary air quantities (amount of air introduced into the front and rear transition of the combustion chamber to the afterburning zone)

L̇ _T

Tertiary air quantity (amount of air introduced in the left and right side walls of the combustion chamber)

T _PL

Primary air temperature

T _I

Temperature fire length (temperature at the outlet end of the firing grid)

T _Hu

Temperature calorific value (temperature at the upstream end of the combustion grate)

ṁ _D

Steam quantity (live steam mass flow, steam quantity)

ṁ _{D, shall}

selected thermal load, target steam quantity

ṁ _{D, is}

Actual steam quantity (measured)

O ₂

Oxygen content (oxygen content in flue gas)

O _{2, shall}

Target oxygen content in the flue gas

O _{2, is}

Actual oxygen content in the flue gas

X _shall , Y _shall , Z _shall

further nominal values

X _is , Y _is , Z _is

other actual sizes

y _F

Control value fixed load controller

y _O2

Control value oxygen content

y _X , y _Y , y _Z

Manipulated variables for the values X, Y, Z

G _F

Weighting factor fixed load

G _O2

Weighting factor oxygen

G _X , G _Y , G _Z

Weighting factors of sizes X, Y, Z

K _F

Correction factor power

K _O2

Correction factor oxygen

K _X , K _Y , K _Z

Correction factors of the further variables X, Y, Z

L̇ _{P (Z1)}

Flow of primary air grate zone 1

Ẇ _R1

Speed rust zone 1
etc. according to the various indices for each additional grate zone 2, 3, 4, and 5.

With reference to Fig. 4 the interaction between manipulated variables and controlled variables with different weighting factors is clarified. The various symbols are intended to represent the various manipulated variables. The matrix representation clarifies that manipulated variables and controlled variables can be linked to one another at will. Finally, the different size of the symbols shows the weighting factor and thus the different parametric influence of manipulated variables and controlled variables.

The Figure 4 is intended to illustrate a matrix with zonal and controller-dependent single weighting factors for the fixed load (GF), the oxygen content (GO2), the calorific value (GHu) and the firing length (G1), where a "big" symbol means a weighting factor of 100%; if there is no symbol in an intersection of the controlled variables, this represents a weighting factor of 0%; Therefore, the bigger the symbol, the bigger the weighting factor. The occupancy of this table can be used to influence the overall control of firing capacity for feed and rust velocities. A weighting of the entire GI line (fire length) with 0%, for example, switches off the fire length controller completely. Any number not equal to 0% will weight the impact for each zone accordingly in the range of -100% to +100%. The air volumes and their distribution and transport speeds are thus influenced by all four controllers, whereas the quenching speed is only changed by the oxygen content , The feed rate is controlled or regulated primarily via the amount of steam, secondarily via the oxygen content in the flue gas.

A close look at the Fig. 4 Also shows that the calorific value and fire length controller for the feed are weighted at 0% - so these two controllers have no effect on the feed rate control. Nor do they have any influence on a change in the quenching speed. A change in the primary air temperature can only cause the calorific value, which makes sense, because the relationship between T _Hu and fire position could be proved. Furthermore, the context applies that by means of an increased primary air temperature T _PL a lower calorific value and thus a lower T _Hu can be counteracted.

In an advantageous development of the invention, a fourth controlled variable D is provided, which is derived from the layer thickness and / or the air permeability of the combustion material located on the firing grate ( Fig. 2 / 16).

The measurement of the controlled variable D is preferably carried out by a in Fig. 2 However, the measurement of the controlled variable D by the pressure sensor 19 can also take place in any zone 1-x or in each zone 1-x. By measuring the controlled variable D in the Primärläftkanal the pressure can be measured, which is opposed to the primary air through the lying on the grate kiln. This makes it possible to draw conclusions about which type of material is on the grate (wet, heavy waste = high primary air pressure, bulky waste = low primary air pressure) and / or in which layer thickness this is present. Thus, one can also detect, for example, if there is on the side of the feed a Pouching or similar disorders, and react accordingly.

LIST OF REFERENCE NUMBERS

1

fire grate

2

charging device

3

firebox

4

throttle cable

5

grate steps

6

drive

7

Under wind chambers

8th

Single lines

9

slag roller

10

Slag chute

11

hopper

12

chute

13

feed table

14

Beschickkolben

15

Beschickkante

16

fuel

17

temperature sensor

18

Air flow measuring device

19

pressure sensor

20a, 20b

temperature sensor

21

Adjusting device Schürgeschwindigkeit

22

Setting device Speed of the slag roller

23

Actuator on and off frequency

24

Actuator Primary air flow

25

gas detector

26

Data acquisition device

27

Evaluation and control circuit

28

switch

symbols

ẇ _B

feed rate

ẇ _Rn

Rust transport speed

ẇ _Sn

Rust stoking

L̇ _ges

total amount of combustion air

L̇ _Pn

Primary air flows

L̇ _Sn

Secondary air volumes

L̇ _T

Quantity of tertiary air

TPL

Primary air temperature

tl

Temperature fire length

T _Hu

Fire position (average temperature)

ṁ _D

steam

O ₂

Oxygen content in the flue gas

Claims (11)

1. Method for controlling the heat output of incinerators, particularly incinerators for solids, with a view to keeping the quantity of steam produced as constant as possible, on the one hand, and with a view to minimising the emission of noxious substances, on the other hand, and a mode of operating said incinerators, which as far as possible avoids damage to the boiler and obviates corrosion of the boiler pipes, wherein material for incineration (16) is fed in at the start of an incineration grate (1), is subjected to a riddling and advancing movement thereon and at the end of the incineration grate (1) the cinder produced is discharged, wherein, in this method, the controlling of the heat output is carried out as a function of at least three regulated variables A, B and C which have been measured or derived from measured values, the regulated variable A being derived from the measured amount of steam ṁ _D,actual, the regulated variable B directly or indirectly indicating at least one type of gas in the emissions, and the regulated variable C being derived from at least one temperature and/or calorific value of the material for incineration (16) associated with the firebed or combustion chamber (3), and the regulation of the control variables being carried out as a function of the at least three regulated variables which have been measured or derived from measured values, in a predetermined, variably adjustable weighting of these regulated variables.
2. Method according to claim 1, characterised in that the regulated variable B directly or indirectly indicates the oxygen content of the emissions.
3. Method according to claim 1 or 2, characterised in that the regulated variable C is determined from the position of the fire and/or the length of the fire in the firebed, the position of the fire being derived from one or more temperatures measured at the start of the grate or temperatures in the after-burning chamber, and the length of the fire being derived from one or more measured temperatures at the output end of the incineration grate (1).
4. Method according to one of the preceding claims, characterised in that the temperature measurements corresponding to the regulated variable C are measured by means of radiation pyrometers.
5. Method according to one of the preceding claims, characterised in that the control variables of the incineration plant that are to be regulated are the charging speed Ẇ _B, i.e. the speed at which the fuel (16) is supplied from the charging device (2) onto the incineration grate (1), the grate transporting speed Ẇ _RN, i.e. the speed at which the incineration material (16) is conveyed over the incineration grate, the grate riddling speed Ẇ _SN, i.e. the speed at which the material for incineration (16) is riddled in the individual zones of the grate, the quantity of primary air L̇ _Pn which is acted upon at the respective grate zone, the quantity of secondary air L̇ _Sn introduced into the front and rear transitions of the combustion chamber (3) into the afterburning zone (4), the quantity of tertiary air L̇ _T introduced in the left and right side walls of the combustion chamber (3), and the primary air temperature TPL.
6. Method according to one of the preceding claims, characterised in that the weighting of the regulated variables is shown in relation to the control variables in the form of weighting factors predetermined in a weighting matrix, the weighting factors being present in a quantity that accords, in particular, with the weighting matrix shown in Figure 3.
7. Method according to one of the preceding claims, characterised in that the weighting factors of the weighting matrix have the following values, based on a standard value of 10: charging speed transporting speed riddling speed air quantity and distribution primary air temperature quantity of steam ṁ _D 9 - 10 9 - 10 0 9 - 10 0 oxygen O₂ 7 - 9 7-9 9-10 5-7 0 position of fire T_Hu 0 2 - 4 0 4 - 6 9 - 10 length of fire T1 0 7 - 9 0 3 - 5 0
8. Method according to one of the preceding claims, characterised in that the control of the heat output is adjusted for different types of fuel, each type of fuel having its own set of parameters for regulating the heat output, the method for controlling the heat output being capable of being switched over to other types of fuel during the operation of the incineration plant.
9. Method according to one of the preceding claims, characterised in that the quantities of air and the distribution of air in the incineration plant are controlled completely separately from the speeds of charging and transporting the material for incineration.
10. Method according to one of the preceding claims, characterised in that in addition to the three regulated variables A, B and C, other regulated variables D, E, F, ... are provided, all the regulated variables being adapted to be combined with one another in any combination, while in particular a fourth regulated variable D is provided which is derived from the layer thickness and/or the air permeability of the material for incineration located on the incineration grate, the fourth regulated variable D allowing conclusions to be drawn as to the nature and/or layer thickness of the material that is on the grate.
11. Apparatus for controlling the heat output of incinerators, particular incinerators for solids, in which material for incineration (16) is supplied at the start of an incineration grate (1), is subjected thereon to a riddling and advancing movement and at the end of the incineration grate (1) the cinder produced is discharged, the apparatus comprising
    a steam measuring device for measuring the amount of steam produced ṁ _D,actual, a regulated variable A being derived from the amount of steam produced ṁ _D,actual,
    a gas detector device for determining the type of gas in the emissions, a regulated variable B being derived from the determination of the type of gas, which directly or indirectly indicates at least a type of gas in the emissions,
    a temperature measuring device that supplies a regulated variable C which is derived from at least one temperature associated with the firebed or the combustion chamber and/or calorific value of the material for incineration (16), and
    a regulating device associated with the steam measuring device, the gas detector device and the temperature measuring device, which controls the heat output with a view to keeping the amount of steam produced ṁ _D,actual as constant as possible, on the one hand, and with a view to minimising the emission of noxious substances, on the other hand, and controlling the mode of operation so as to avoid damage to the boiler as far as possible and obviate corrosion of the boiler pipes, as a function of the at least three regulated variables A, B and C which have been measured or derived from measured values, the regulation of the control variables being carried out as a function of the at least three regulated variables which have been measured or derived from measured values, in a predetermined, variably adjustable weighting of these regulated variables.

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