EP0718553B1 - Method of combustion of wastes - Google Patents

Abstract

The waste burning method involves passing the waste (1) via a feed shaft (2) and an output slider (3) for burning on a burner (4) to which air is fed to maintain combustion. At least one parameter which influences the combustion is controlled according to the calorific value of the waste to be burnt. The calorific value, or a parameter defining it, is determined in the feed shaft using a microwave technique and the resulting measurement value stored in a process control unit (9). The process control unit controls the quantity of air and/or waste fed to the burner depending on the magnitude of the calorific value of the waste.

Description

TECHNICAL AREA

The invention relates to a method for the combustion of Waste through an allotment shaft and a feed pusher are transported to a grate for burning air is supplied to maintain combustion.

The invention further relates to a device for Performing this procedure.

The invention is based on a prior art, such as it results, for example, from EP-A-0 317 731.

TECHNOLOGICAL BACKGROUND AND PRIOR ART

Waste is seen as fuel in its composition very inhomogeneous. Their properties such as calorific value, ignitability and burn rate fluctuate in a very wide range. Waste comes to incineration, for example from organic residual waste, industrial waste, wood, stones, plastics, Glass, ceramics, paper and cardboard are made. The trash should be used in such a combination for combustion provided that always a certain amount of combustible Ingredients is included. The intended for combustion There are different sizes of waste. In addition they have different proportions of water, which at the combustion must be taken into account. In contrast to are the compositions and the chemical-physical properties known from fuels such as coal, gas and oil. in the In contrast to the waste mentioned above, it is no problem possible an incinerator for these fuels to optimize.

Incineration plants for waste have so far mostly been low Degree of automation driven. Most of the previously known Facilities of this type are provided with a control room is looked after by at least one surgeon. The operator is responsible the task of managing the combustion in each case Adjust fuel. He is on his personal observation the combustion process. Most of them Incinerators is at least one video camera provided, which is arranged above the combustion chamber. Corrective Interventions in the combustion process can, however only be carried out retrospectively, i.e. then when there is a change the composition of the waste to be incinerated has noticed a change in the quality of combustion. Then it is usually already for corrective interventions too late. Such a combustion process is becoming more and more or fluctuate less strongly around its optimal operating point. In order to minimize these fluctuations, approaches can be identified the degree of automation of waste incineration to increase. For this purpose, new sensors are installed in the combustion chamber installed that watch the combustion process. The information obtained here, which the surgeon up to now visually recorded, are automatically recorded and immediately a combustion control system as a correction factor made available.

EP-A-0 317 731 proposes to observe the area of the waste application on the combustion grate with optical radiation receivers which are preceded by optical filters which selectively detect the electromagnetic radiation emitted by H ₂ O or CO ₂ molecules. The indicator for the water content of the waste obtained in this way is fed to the control device as a disturbance variable for controlling the combustion. With the method described here, a signal is obtained which provides information about the water content of the waste before the waste is incinerated, so that the combustion parameters can be adapted directly to the incinerating waste. However, a disadvantage of this method is that the time from the drop in the waste in the drop zone to the incineration on the grate is too short for changes in the combustion parameters to have a positive effect. The dead times in this process are in the order of 30 to 60 minutes. The transport time from the waste disposal area to the main incineration zone, on the other hand, is in the range of 10 minutes. In the method described here, the water content of the waste is determined only by the water evaporating on the surface. The water contained and bound inside the waste is not recorded and can therefore not be taken into account when controlling the combustion.

EP-A-0 352 620 describes a method in which the grate on which the waste is incinerated with With the help of a video camera is observed. The video image received is processed automatically using a computer. The signals obtained from this turn into information about the course of combustion, such as the temperature distribution and derived the location of the main fire zone and then fed to the process control system as a control variable. With this method, a predictive driving style is the Waste incineration is not possible because only the surface temperature on the grate is detected. Embers or smoldering nests under the surface of the garbage to be incinerated, which is the incineration process influence, are disregarded.

BRIEF SUMMARY OF THE INVENTION

The invention is therefore based on the object of a method to demonstrate that a predictive driving style of combustion of waste of all kinds, so that already before the incineration of the pending waste is known which parameters the furnace is to be set. The invention is also the object of one with this method demonstrate operable waste incineration facility.

Starting from the prior art, this object is achieved according to the invention solved in that the calorific value or at least a parameter that determines the calorific value for combustion upcoming waste (1) is already determined in the allocation shaft (2) and the measurement values determined from this in a process control unit (18) are saved, which are dependent on the size of the calorific value during combustion of waste (1) the amount of air to be fed to the grate and / or controls the amount of waste to be fed to the grate.

A corresponding facility for the incineration of waste is the subject of claim 11.

The calorific value of the waste to be incinerated or one their determining calorific value determines a certain size Time before the combustion in the allocation shaft recorded and calculated.

Perpendicular to the conveying direction of the allocation shaft, in which the waste becomes one for the Combustion provided rust are transported, microwave signals sent out. Due to the water content of the waste signal weaknesses and / or phase changes these microwave signals. These are used to determine of the water content in the waste was evaluated. The information signals determined from this are the Process control unit fed.

The device for incinerating waste according to the invention is equipped with an allocation shaft, which is a feed slide is connected downstream. With it becomes the one to be burned Amount of waste on a designated Rust promotes air to maintain the combustion is fed. Inside the allocation shaft is at least a device for recording the calorific value of the waste is installed, connected to at least one evaluation unit are. The signal outputs of the evaluation units are on one Process control unit is connected. This is for the Control of the air supply to the grate or to control the feed slide intended.

The invention is explained in more detail below with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWING

Fig. 1

eine Einrichtung zur Verbrennung von Abfällen im Vertikalschnitt:

Fig.2

den mit einer Mikrowellenanordnung zur Erfassung des Heizwerts der Abfälle versehenen Zuteilungsschacht der Einrichtung gemäss Fig.1;

Fig.3

den mit einer Einrichtung zur Messung des elektrischen Widerstandes der Abfälle versehenen Zuteilungsschacht der Einrichtung gemäss Fig.1;

Fig.3a

einen Schnitt durch die Wandung des Zuteilungsschachtes gemäss Fig.3.

Exemplary embodiments of the invention are shown schematically in the drawings. It shows

Fig. 1

a device for the incineration of waste in vertical section:

Fig. 2

the allocation shaft of the device according to FIG. 1 provided with a microwave arrangement for recording the calorific value of the waste;

Fig. 3

the allocation shaft of the device according to FIG. 1 provided with a device for measuring the electrical resistance of the waste;

Fig.3a

a section through the wall of the allocation shaft according to Figure 3.

WAYS OF CARRYING OUT THE INVENTION

The device for incinerating waste shown in Fig.1 1 of all types includes an upright allocation shaft 2 with rectangular cross-section, a feed slide 3 at its lower end for dosing and conveying the waste 1 on a grate attached to it 4. In one Design section 5 of the allocation shaft 2 is a general one measuring device designated by reference numeral 6 for Determination of the calorific value of the waste there 1 intended. The dimensioning section is designed in such a way that the time between passing waste 1 and task on the grate is typically 20 to 30 minutes.

In a first preferred embodiment of the invention to determine the water content in these wastes 1 - this determines their calorific value - is in the design section 5 of the allocation shaft 2, a microwave measuring arrangement 6 provided. According to FIG. 2, this comprises the Dimensioning section 5 of the allocation shaft 2 in an enlarged view View shows two spatially distant measuring points with combined microwave transmitter / receiver modules 6a, 6b, 6c, 6d, 6a ', 6b', 6c ', 6d'. Here are in two perpendicular to each other lying and perpendicular to the conveying direction of the allocation shaft 2 extending levels α and β four each Combined microwave transmitter / receiver modules 6a, 6b, 6c, 6d or 6a ', 6b', 6c ', 6d' on the inside of the wall 2A of the Allocation shaft 2 arranged. The two measuring points is each assigned an evaluation unit (8,8 '), whose output signals are fed to the process control unit 9.

Two microwave transmitter / receiver modules 6a and 6b or 6c and 6d are on a straight line perpendicular to the conveying direction the allocation shaft 2 arranged opposite each other are. The microwave transmission / reception modules belonging to the level β are in the same way 6a ', 6b', 6c ', 6d' arranged.

The microwave arrangements can consist of separate transmitters Receiving modules exist, which are located on the walls of the allocation shaft opposite. But it can also be combined Transmit / receive modules. In the first case it will Transmittance of waste recorded using microwaves. In the second case the reflectivity of the waste determined. A third option is in the design section 5 standing microwaves to generate and amplitudes and / or to detect phase changes in the microwaves, which in turn draw conclusions about the water content or the Allow calorific value of waste.

The amount of waste 1 that is incinerated on the grate 4 is loaded corresponds to the amount of waste entering the design section 5 of the allocation shaft 2 can be filled can. From signal weakening and / or phase changes the microwave signals can be analyzed using the evaluation unit 8 the water content and thus within certain error limits the calorific value of the transported in the design section 5 Waste 1 can be determined. The measurement in two separate Levels a and β prevent misinterpretations, e.g. if a larger piece of metal M is carried in the waste. The evaluation unit 8 sends a signal with the information to the process control unit via the water content or calorific value 9 forwarded.

These signals represent the incineration of waste 1 Control of the air supply to grate 4 is available. The one in the Allocation shaft 2 contained waste 1 with the help of Feed slide 3 transported to the grate for combustion. The Amount of waste 1 that is loaded onto the grate 4 corresponds the amount of waste currently in the design section 5 of the allocation shaft 2 is located. With help the feed slide 3 can exactly the amount of waste 1 the grate 4 are transported, the water content of which e.g. 30th Minutes before combustion when filling in the dimensioning section 5 was determined. To make a correct assignment between the measured values stored in the process control unit be put on the grate for combustion Ensure transported waste 1, the feed pusher 3 also controlled by the process control unit 9.

An air flap 10 is also provided by the process control unit 9 controlled in a pipe 11 below the grate 4th is arranged. This opens into channels 12 on the underside the grate 4, from where the grate 4 is for optimal combustion required amount of air is supplied.

An alternative way to determine the calorific value of the waste is shown schematically in Fig.3 and Fig.3a. in the Design section are on or in two opposite Walls of the top surface electrodes 13 and 14 are arranged. This are from the wall of the feed shaft, which is regularly made of metal 2 electrically isolated by means of insulators 15. How 3a can be seen, there is the insulator 15 T-shaped cross-section, with the inward-facing Leg has the same length as the wall thickness of the feed shaft and electrodes 13 and 14. In this way the garbage does not slide through the isolator nor the electrode is obstructed. It is attached from the outside. au By means a combined feed and current measuring device 16 is a current - supplied by a constant voltage source - passed through waste 1 in assessment section 5. The The size of the flowing current I is a measure of volume conductivity of waste and this in turn is a measure of the water content and thus the calorific value of the waste. The output signal the combined feed and current measuring device 16 is fed to the process control unit 9.

Analogous to the microwave measurement method described above can also do two with regard to the flow direction of the waste electrode arrangements spaced apart from one another are provided to avoid incorrect measurements e.g. as a result of being carried in the waste to avoid larger pieces of metal.

The density of waste 1 is determined using separate methods. This can e.g. by making the weight of the Waste column in the feed chute above that of the feed pusher 3 by means of load cells 17, which are in the supporting structure of the Feed slide are integrated, is measured. This information is also stored in the process control unit and taken into account when controlling the combustion. By Comparison of the weight of these waste columns to different ones Times can be combined in e.g. with the water content make a statement about the waste quality or the calorific value. Furthermore, the flow rate of the waste in the supply shaft can also 2 e.g. with a measuring wheel 18 that with a tachometer generator is coupled, determined and also via an associated evaluation unit 19 of the process control unit 9 are supplied.

• die erzeugte Dampfmenge als weitere Führungsgrösse
• der O2-Gehalt im Rauchgas als Störgrösse für die Dampfmenge als (weitere) Führungsgrösse
• der O2-Gehalt im Rauchgas neben der Müllqualität als weitere Führungsgrösse für den Verbrennungsprozess
• die Dampfmenge als Störgrösse auf den O2-Gehalt als Führungsgrösse
• die Steuerung der Abfallbeschickung über den Aufgabeschieber in Abhängigkeit von der Müllqualität, dergestalt, dass Anzahl und Grösse der Zuteilportionen (der zuzuteilenden Abfallportion) selbstätig an die Müllqualität angepasst werden, wobei die Anzahl und Grösse der Zuteilportionen, z.B. über die Hublänge des Aufgabeschiebers, leistungsabhängig festgelegt werden
• die Abfallschichtdicke über dem Verbrennungsrost, die z.B. über die Strömungswiderstände durch Rost und Abfallbett erfassbar und regelbar ist. Auf diese Weise lässt sich ein Ueberfüllen des Rostes verhindern und das Leerfahren des Rostes vermeiden. Dabei können auch die einzelnen Unterwindzonen des Rostes getrennt erfasst und der Müllqualität entsprechend geregelt werden.
• Erfassung der Primärluftverteilung in den Unterwindzonen und deren Steuerung/Regelung in Abhängigkeit von der Müllqualität
• Primärlufttemperatur über den Luftvorwärmer und daneben auch deren Verteilung aaaauf die einzelnen Unterwindzonen in Abhängigkeit von der Müllqualität
• Variation der Rostgeschwindigkeiten in den einzelnen Rostzonen in Abhängigkeit von der Müllqualität
• Beschickte Abfallmenge aufgrund der Fliessgeschwindigkeit des Abfalls im Zuteilungsschacht
• Strömungswiderstände in den einzelnen Unterwindzonen zur Regelung der Feuerlage.

The method described above for the incineration of waste with a forward-looking mode of operation is particularly suitable for process control in the incineration of heterogeneous waste, in particular waste. The waste quality is the overriding benchmark in the regulation and control of the incineration process in such a way that the waste quality is used as a guiding parameter for the essential actuators of the incineration process. Waste quality in the form of calorific value and water content is the main guiding parameter. In addition, a number of other command variables and disturbance variables play a role, which can be taken into account individually or in combination:

• the amount of steam generated as a further benchmark
• the O2 content in the flue gas as a disturbance variable for the amount of steam as a (further) reference variable
• the O2 content in the flue gas in addition to the waste quality as a further guide variable for the combustion process
• the amount of steam as a disturbance variable on the O2 content as a reference variable
• the control of the waste loading via the feed pusher depending on the waste quality, such that the number and size of the portion portions (the portion of waste to be allocated) are automatically adjusted to the waste quality, the number and size of the portion portions being determined depending on the output, e.g. via the stroke length of the feed pusher will
• the thickness of the waste layer above the combustion grate, which can be detected and regulated, for example, by the flow resistances through the grate and waste bed. This prevents overfilling of the grate and prevents the grate from running empty. The individual underwind zones of the grate can also be recorded separately and regulated according to the waste quality.
• Detection of the primary air distribution in the underwind zones and their control / regulation depending on the waste quality
• Primary air temperature above the air preheater and also its distribution aaa to the individual underwind zones depending on the waste quality
• Variation of the grate speeds in the individual grate zones depending on the waste quality
• Quantity of waste loaded due to the flow rate of the waste in the allocation shaft
• Flow resistances in the individual underwind zones to control the fire situation.

Label list

1

Waste

2nd

Allocation shaft

3rd

Feed pusher

4th

rust

5

Design section of 2

6

Device for determining the calorific value of 1

6a, ...

Microwave arrangements

8.8 '

Evaluation units

9

Process control unit

10th

Air damper

11

Pipeline

12th

Air ducts in 11

13.14

plate-shaped electrodes

15

Isolators

16

combined feeding and measuring device

17th

Load cells

18th

Measuring wheel

19th

Evaluation unit for 17th

Claims (16)

1. Method for the incineration of waste materials (1) which are conveyed onto a grate (4) for incineration via a metering shaft (2) and a feeder slide (3), to which grate (4) air is supplied to maintain the incineration, at least one parameter which affects the incineration being controlled as a function of the calorific value of the waste material to be incinerated, characterized in that the calorific value or at least a measurement variable, which determines the calorific value, of the waste materials (1) available for incineration is already determined in the metering shaft (2), and the measurement values determined therefrom are stored in a process control unit (9) which controls the quantity of air to be supplied to the grate and/or the quantity of the waste material to be supplied to the grate as a function of the magnitude of the calorific value during the incineration of the waste materials (1).
2. Method according to Claim 1, [lacuna] in that the calorific value of the waste materials (1) available for incineration is determined at a given time prior to the feed onto the grate (4).
3. Method according to either Claim 1 or 2, characterized in that the calorific value of the waste materials (1) is determined 30 minutes prior to the incineration within a measuring portion (5) of the metering shaft (2) which has a defined magnitude.
4. Method according to one of Claims 1 to 3, characterized in that microwaves are transmitted within the measuring portion (5) perpendicular to the conveying direction of the metering shaft (2), and signal attenuations and/or phase shifts of these microwaves are evaluated to determine the calorific value in the waste materials (1) available for incineration.
5. Method according to one of Claims 1 to 4, characterized in that microwaves are transmitted perpendicular to the conveying direction of the metering shaft (2) from the inner side of a first wall of the measuring portion (5) to the opposite wall and are received there and, when the microwaves pass through the waste materials (1), the water content thereof is calculated from the signal attenuation and/or phase shift of the microwaves received, and the measurement values determined are stored in the process control unit (9).
6. Method according to one of Claims 1 to 5, characterized in that microwaves microwaves [sic] are transmitted perpendicular to the conveying direction of the metering shaft (2) from the inner side of a first wall of the measuring portion (5), and the signal changes of the microwaves reflected on the waste materials (1) are evaluated to determine the water content in these waste materials (1), and the measurement values determined are stored in the process control unit (9).
7. Method according to one of Claims 1 to 6, characterized in that at least one vertical microwave is formed inside the measuring portion (5) between two opposite walls (2A, 2B) to determine the water content in waste materials (1), and the water content of the waste materials (1) available for incineration is determined from the signal attenuation and/or phase shift of this vertical microwave, and the measurement values is [sic] stored in the process control unit (9).
8. Method according to one of Claims 1 to 7, characterized in that the microwave signals transmitted and received are passed to an evaluation unit (8) to determine the water content in the waste materials (1) available for incineration, which evaluation unit calculates, from the differences between the microwave signals transmitted and received, the water content of the waste materials (1) checked and passes an information signal on to the process control unit (9).
9. Method according to one of Claims 1 to 3, characterized in that the electrical resistance in the waste materials available for incineration is measured perpendicular to the conveying direction of the metering shaft (2) within the measuring portion (5), which electrical resistance is evaluated to determine the calorific value in the waste materials (1) available for incineration.
10. Method according to one of Claims 1 to 9, characterized in that, in addition to the calorific value of the waste materials (1) available for incineration, their flow rate and/or their weight are determined in the metering shaft and are evaluated in the process control unit (9).
11. Apparatus for the incineration of waste materials, having a metering shaft (2), downstream of which a feeder slide (3) is disposed, which conveys the quantity of waste materials (1) to be incinerated in each case onto a grate (4) which is provided for this purpose and to which air can be supplied to maintain the incineration, characterized in that at least one measuring device (5) is installed within the metering shaft (2) to determine the calorific value of the waste materials (1) and is connected to at least one evaluation unit (8; 16) whose signal outputs is [sic] connected to a process control unit (9) which is provided for controlling the air supply to the grate (4) and/or for controlling the feeder slide (3).
12. Apparatus according to Claim 11, characterized in that the measuring device (5) is installed within the measuring portion (5) of the metering shaft (2) and has microwave transmitters, microwave receivers or combined microwave transmission/reception modules which are connected to the evaluation unit (8) and whose signal output is connected to the process control unit (9).
13. Apparatus according to either Claim 11 or 12, characterized in that at least four combined microwave transmission/reception modules (6a, 6b, 6c, 6d and 6a', 6b', 6c', 6d') are provided respectively in two planes (Â and β) lying vertically one below the other and running perpendicular to the conveying direction of the metering shaft (2).
14. Apparatus according to Claim 11, characterized in that two plate-shaped electrodes (13, 14) are provided on the inner side of two opposite walls of the metering shaft (2), which electrodes are electrically insulated from said walls and are connected to a voltage source (16) which comprises a current measuring device for recording the current through the waste material located in the feeder shaft.
15. Apparatus according to one of Claims 11 to 14, characterized in that means are provided for recording the weight of the waste materials (1) in the metering shaft (2).
16. Apparatus according to one of Claims 11 to 15, [lacuna] in that means (18, 19) are provided in the metering shaft for recording the flow rate of the waste material in the metering shaft (2).

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