US20050066865A1

US20050066865A1 - System for continuous thermal combustion of matter, such as waste matter

Info

Publication number: US20050066865A1
Application number: US10/220,012
Authority: US
Inventors: Lambertus Bernardus Van Kessel
Original assignee: Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek TNO
Current assignee: Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek TNO
Priority date: 2000-02-28
Filing date: 2001-02-27
Publication date: 2005-03-31
Also published as: JP2003525418A; WO2001065178A1; AU2001241269A1; EP1259760A1

Abstract

The system for continuous thermal combustion of matter, such as waste matter, is provided with an incinerator comprising an inlet, an outlet and a combustion path extending between the inlet and the outlet. The system further comprises air supply means for supplying heated air to the combustion path. The system is further provided with regulating means for automatically regulating the magnitude of the air supply and/or the temperature of the air supplied with the aid of the air supply means, depending on the heating value of the matter (the amount of heat which is generated upon combustion of the matter in the incinerator).

Description

BACKGROUND OF THE INVENTION

1. Field Of The Invention
The invention relates to a system for continuous thermal combustion of matter such as waste matter, provided with an incinerator comprising an inlet for supplying matter to be burned, an outlet for removing burned matter, a combustion path extending between the inlet and the outlet and along which, in use, the matter is continuously transported in a transport direction from the inlet to the outlet for combustion of the matter, and air supply means for supplying heated air to the combustion path. The invention also relates to a method for continuous thermal combustion of matter such as waste matter, in an incinerator comprising an inlet for supplying matter to be burned, an outlet for removing burned matter, a combustion path extending between the inlet and the outlet and along which, in use, the matter is continuously transported in a transport direction from the inlet to the outlet for combustion of the matter, and air supply means for supplying heated air to the combustion path.
2. Prior Art
A problem occurring when combusting matter such as, for instance, waste matter, is a fluctuation in the combustion process, caused by the continuously changing composition of the waste matter. Wide fluctuation in the composition and therefore in the energetic power supplied can result in wide process fluctuations, such as fluctuations in temperatures of combustion, which can be detrimental to the system. Such process fluctuations can also result in product fluctuations, such as fluctuations in the amount of steam and electricity generated. As a result thereof, the yield and quality of the products is reduced. What is understood here by ‘products’ are both the burned waste matter and the energy and/or steam generated by the combustion.

SUMMARY OF THE INVENTION

The object of the invention is to provide a solution to the drawbacks outlined above.
The system according to the invention is characterized in that the system is further provided with regulating means for automatically regulating the magnitude of the air supply and/or the temperature of the air supplied with the aid of the air supply means, depending on the heating value of the matter (the amount of heat which is generated in the incinerator upon combustion of the matter per kilogram of matter) and/or the location of the fire in the combustion path.
Hence, according to the invention, the air supply is regulated depending on the combustion, so that the above-mentioned process fluctuations are counteracted.
The invention is based on the insight that a higher heating value of the matter to be burned will result in a fire of longer extension along the combustion path. Hence, the heating value and the location of the fire are closely connected. By determining the heating value or the location of the fire, process fluctuations resulting from fluctuations in the heating value can be compensated by regulating the magnitude of the air supply and/or the temperature of the air supplied. In consequence, with an increasing heating value and/or associated expansion of the fire In the direction of the inlet, the magnitude of the air supply can be reduced and/or the temperature of the air supplied can be reduced, vice versa.
In a manner known per se, the heating value of the matter can be determined, for instance, by determining the composition of the matter.
In particular, the combustion path, viewed in the transport direction of the matter along the combustion path, is provided with at least a first combustion zone for heating and evaporating the platter, a main combustion zone in which the matter is substantially burned, and a final zone for burnout, respectively, the regulating means being arranged to regulate, depending on the heating value of the matter in the incinerator and/or the location of the fire in the combustion path, the magnitude of the air supply to the main combustion zone. In particular, even with a sufficiently high heating value, the air supply to the main combustion zone can be closed off.
According to a preferred embodiment of the system according to the invention, the regulating means are provided with sensor means for obtaining information about a position in the combustion path where fire is located. More in particular, in such case, the regulating means are arranged for reducing the temperature of the air supplied when the fire expands along the combustion path in the direction of the inlet and for increasing the temperature of the air supplied when the fire moves away from the inlet. It is also possible that the regulating means are arranged for reducing the magnitude of the air supply when the fire expands along the combustion path in the direction of the inlet and for increasing the magnitude of the air supply when the fire moves away from the inlet.
According to a further elaboration of the system according to the invention, the regulating means are arranged for closing off the air supply to the main combustion zone when the fire expands beyond a predetermined position in the combustion path in the direction of the inlet and for releasing the air supply to the main combustion zone again when the fire moves away from the inlet beyond a predetermined position in the combustion path.
According to a further elaboration, the regulating means are arranged for lowering the temperature of the air supplied when the heating value increases and for increasing the temperature of the air supplied when the heating value decreases. Additionally, according to a further elaboration of this variant, the regulating means are arranged for reducing the magnitude of the air supply when the heating value increases and, for increasing the magnitude of the air supply when the heating value decreases.
The method according to the invention is characterized in that, depending on the magnitude of the heating value of the matter (the amount of heat which is generated in the incinerator upon combustion of the matter. Per kilogram of matter) and/or the position of the fire in the combustion path, the magnitude of the air supply and/or the temperature of the air supplied with the aid of the air supply means, is/are regulated.

BRIEF DESCRIPTION OF THE DRAWING

The system and the method according to the invention will now be further elucidated with reference to the drawing. In the drawing:
FIG. 1 shows a possible embodiment according to the invention for a system of continuous thermal combustion of matter.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1, with reference number 1, a system for continuous thermal combustion of matter, in this example, waste matter, is indicated. The system 1 is provided with an incinerator 2, comprising an inlet 4 for supplying the matter to be burned. Further, the incinerator comprises an outlet 6 for removing the matter which has been burned in the incinerator. In the incinerator, a combustion path 8 extends between the inlet 4 and the outlet 6.
In use, the matter 3 is transported along the combustion path 8 in a transport direction 10 from the inlet 4 to the outlet 6 for combustion of the matter. Here, the incinerator is provided with a grate 12, known per se, comprising means for displacing the matter over the grate in the transport direction 10.
The system is further provided with air supply means 14 for supplying heated air to the combustion path 8. The combustion path 8, viewed in the transport direction 10 of the matter along the combustion path 8, is provided with at least a first combustion zone 16, a main combustion zone 18 and a final zone 20, respectively. In the first combustion zone, the matter is heated and, further, evaporation of moisture contained in the matter will occur. In the main combustion zone, at least substantially, the combustion of the matter occurs. In the final zone 20, the matter will burn out, so that the fire, at the outlet 6, is extinguished. The system can be further provided with a chimney 40 having a variable exhaust 42. In this example, the exhaust 42 is also controlled by the control means 26. Additionally, in the chimney, a dust catcher 44, known per se, is included. Via a channel 46, at least a part of the flue gases which leave the incinerator via the chimney 40 and which have been stripped of dust with the aid of the device 44, can be returned to the incinerator. This involves so-called waste gas recirculation. Additionally, near the chimney, an inlet 48 with a control valve 50 can be disposed, via which inlet secondary air can be supplied to the incinerator. The control means 26 can further be arranged to control the control valve 50 via a line 52.
The system is further provided with regulating means 22 adapted, depending on the heating value of the matter in the incinerator (this is the amount of heat generated upon combustion of the matter 3 in the incinerator per kilogram of the matter), to automatically regulate the magnitude of the air supply and/or the temperature of the air supplied with the aid of the air supply means 14. To that end, in this example, the regulating means comprise sensor means 24 for obtaining information about the heating value and control means 26 which are connected to the sensor means 24 via a line 28. On the basis of information supplied by the sensor means 24 via the line 28 to the control means 26, the control means 26 generate a control signal which is fed, via a line 30, to the air supply means 14. To that end, in this example, the control means 26 consist of a suitably programmed computer 26. With the aid of the control signal, the magnitude of the air supply to the combustion path and/or the temperature of the air supplied to the combustion path can be regulated. The regulation is such that, when the heating value increases (so that the temperature in the incinerator will increase), the magnitude of the air supply decreases and/or the temperature of the air supplied decreases. As a result, the temperature will decrease again. When, on the other hand, the heating value decreases (so that the temperature in the incinerator will decrease) the regulation is such that the magnitude of the air supply to the combustion path increases and/or the temperature of the air supplied to the combustion path increases. As a result, the temperature will increase again. The regulation, therefore, is such, that fluctuations in the temperature combustion process (temperature fluctuations) are counteracted and are thus damped. In particular, generally only the magnitude of the amount of air which is supplied to the main combustion zone is regulated with the aid of the air supply means 14. It may even be so that the regulating means are arranged for closing off the air supply to the main combustion zone entirely when the heating value exceeds a predetermined value.
In particular, the sensor means 24 are arranged for obtaining information about a position in the combustion path where the fire of the combustion is located. To that end, the regulation means 22 can, for instance, be provided with an infrared camera, a CCD camera and the like. The regulating means can then be arranged such, that the magnitude of the air supply and/or the magnitude of the temperature of the air supplied is reduced when the fire expands in the combustion path in the direction of the inlet 4. When the fire moves away from the inlet 4, the regulating means will then cause the magnitude of the air supply and/or the height of the temperature of the air supplied to increase again. More in particular, when the fire expands beyond a predetermined position 32 in the direction of the inlet 4, so that the fire approaches the inlet 4, the regulating means 22 will reduce the magnitude of the air supply and/or the temperature of the air supplied, so that the distance between the inlet 4 and the nearest position in the combustion path where the fire is located, will increase again. When the fire has moved away from the inlet beyond the predetermined second position 34, the magnitude of the air supply and/or the temperature of the air supplied will not be further reduced. It will be clear that the increase or decrease of the air supply, or the temperature, will be slowly varied in time because the fire in the incinerator needs some time to adjust to the new air supply. Varying the magnitude of the air supply and/or the temperature can be executed both continuously and in discrete steps. In this example, the first position 32 and the second position 34 are located at some distance from one another in order to prevent an unstable regulation. Therefore, in this example, the system comprises a hysteresis loop.
The regulation means can further be arranged for closing off the air supply to the main combustion zone 18 when the fire expands beyond the predetermined position 32 in the combustion path in the direction of the inlet, and for releasing the flow of air which is supplied to the main combustion zone when the fire has moved away from the inlet 4 beyond the predetermined position 34.
These sensor means 24 can also be arranged for determining, in a manner known per se, the composition of the matter 3. With the aid of this composition, the control means 26 can determine, in a manner known per se, the heating value of the matter 3 in order to regulate the magnitude of the air supply and/or the temperature of the air supplied. To that end, the sensor means 24 can, for instance, be provided with a gas chromatograph, a spectrum analyzer and/or a mass spectrograph.
The invention is in no way limited to the above outlined embodiments. The combustion path, for instance, can be provided with more than three zones, the air supply of one or several of these zones being selectively regulated as discussed hereinabove, depending on the location of the fire in the incinerator. In this example, the heating value is determined on the basis of the emission spectrum measured. However, it is also conceivable that the heating value is determined in another manner known per se for regulating the air supply. As already said, the regulation of the air supply can be executed both continuously and in steps. The speed of the regulation can be adapted to the size of the incinerator. Such variants are all understood to fall within the scope of the invention.

Claims

1. A system for continuous thermal combustion of matter such as waste matter, provided with an incinerator comprising an inlet for supplying matter to be burned, an outlet for removing burned matter, a combustion path extending between the inlet and the outlet and along which, in use, the matter is continuously transported in a transport direction from the inlet to the outlet for combustion of the matter, and air supply means for supplying heated air to the combustion path, wherein the system is further provided with regulating means for automatically regulating at least one of the magnitude of the air supply and the temperature of the air supplied responsive to the heating value of the matter determined on the basis of the amount of heat which is generated in the incinerator upon combustion of the matter, per kilogram of matter, characterized in that the regulating means include sensor means for determining the heating value of the matter in the incinerator.

2. A system according to claim 1, wherein the combustion path, viewed in the transport direction of the matter along the combustion path, is divided into at least a first combustion zone for heating and evaporating the matter, a main combustion zone in which the matter is substantially burned, and a final zone for burnout of the matter, respectively, and wherein the regulating means are arranged for regulating the magnitude of the air supply to the main combustion zone, in response to the heating value of the matter in the incinerator.

3. A system according to claim 1 wherein the regulating means reduces the temperature of the air supplied when the heating value increases and increases the temperature of the air supplied when the heating value decreases.

4. A system according to claim 1, wherein the regulating means reduces the magnitude of the air supplied when the heating value increases and increases the magnitude of the air supplied when the heating value decreases.

5. A system according to claim 1 wherein the regulating means closes off the air supply to the main combustion zone when the heating value exceeds a first predetermined value and releases the air supply to the main combustion zone again when the heating value decreases below a second predetermined value.

6. A system according to claim 1 wherein, the sensor means are located in the incinerator.

7. A method for continuous thermal combustion of matter, such as waste matter, in an incinerator comprising supplying matter to be burned into an inlet of a combustion path through the incinerator, removing burned matter from an outlet of the combustion path, continuously transporting matter to be burned in a transport direction from the inlet to the outlet for combustion of the matter, supplying heated air to the combustion path, sensing the magnitude of the heating value of the matter being burned in the incinerator, feeding the sensed magnitude of the heating value to a control station and controlling at least one of the magnitude and temperature of the supply of heated air to the combustion path responsive to the sensed magnitude of the heating value of the matter being generated in the incinerator upon combustion of matter, on a per kilogram of matter basis.

8. A method according to claim 7, wherein the temperature of the air supplied is reduced when the heating value increases and the temperature of the air supplied is increased when the heating value decreases.

9. A method according to claim 7 wherein the magnitude of the air supply is reduced when the heating value increases and the magnitude of the air supply is increased when the heating value decreases.

10. A method according to claim 7 wherein the combustion path, viewed in the transport direction of the matter along the combustion path, is divided into at least a first combustion zone for heating and evaporating the matter, a main combustion zone wherein the matter is substantially burned, and a final zone for burnout of the matter, respectively, while, depending on the heating value, the magnitude of the air supply to the main combustion zone is regulated.

11. A method according to claim 10, wherein the air supply to the main combustion zone is closed off when the heating value exceeds a predetermined value and the air supply is released again when the heating value decreases below a predetermined value.