WO1990009552A1

WO1990009552A1 - Process and device for measuring the radiation emitted at at least two spatially separate points in a combustion process and for controlling the combustion process in function of the measured radiation

Info

Publication number: WO1990009552A1
Application number: PCT/EP1990/000225
Authority: WO
Inventors: Klaus Dieter Rennert
Original assignee: L. & C. Steinmüller Gmbh
Priority date: 1989-02-14
Filing date: 1990-02-12
Publication date: 1990-08-23
Also published as: DE59009747D1; EP0458822A1; DD292068A5; EP0458822B2; DE3904272A1; DE3904272C3; EP0458822B1; DE3904272C2

Abstract

Process for measuring the radiation emitted at at least two spatially separate points during a combustion process and for controlling the combustion process in function of the measured radiation, and device for implementing the process. To improve monitoring of the combustion, the radiation from combustion on a grate is measured by detection of the radiation emitted essentially by individual combustion zones of the grate and the primary air supply to the individual combustion zones and/or the flow rate of the fuel in the individual zones is controlled in function of the measured radiation.

Description

- 1 -

description

Method for detecting the radiation emanating from at least two spatially separated points in a combustion process and regulating the combustion process as a function of the radiation detected and device for carrying out the method

The invention relates to a method for detecting the radiation emanating from at least two spatially separated points in a combustion process and regulating the combustion process as a function of the detected radiation.

As is apparent from DE-PS 35 08 253, the flame monitoring of the individual flames is essential when operating large industrial combustion plants, in particular boilers with dust firing by fossil fuels. The problem here is that, on the one hand, each flame must be equipped with a flame monitor, on the other hand, the walls of the combustion chamber themselves radiate strongly after some operating time.

In addition to the dust combustion, the grate furnaces are becoming increasingly important, as they are particularly suitable for combustion ^'of Hull. With such furnaces, the firing power controls are limited when they intervene in the Firing on the allocation of the primary air usually supplied from below to the grate, the secondary air supplied above the grate and the conveying speed of the feeder with which the waste is supplied to the grate, and the conveying speed on individual grate zones if such a different conveying speed is provided is. It is customary to add the primary air as seen in the conveying direction of the grate in individual sections, depending on the needs of the combustion progress achieved. So far, however, this has only been done by hand lung, since no automatically ascertainable evaluation criteria for the combustion progress in the individual rust zones are known.

The object of the present invention is to provide a method for monitoring combustion which generates automatically ascertainable evaluation criteria for the progress of combustion and enables automation of the control.

This object is achieved in that, in order to detect the radiation from a combustion on a grate, the radiation emanating essentially from individual combustion grate zones of the grate is detected and, depending on the radiation detected, the primary air supplied to the individual combustion zones and / or the

Transport speed of the fuel is regulated in individual zones.

Through the use of a thermographic process, it is possible to record the temperature of the material bed formed on the grate over a large area, that is, to map a two di meni ona Len temperature course in individual grate zones and thus, depending on the recorded temperature image, the primary air supplied to the individual combustion zones and / or the transport speed of the To regulate fuel in individual zones. ^• -

The zoning can be done not only in the funding direction, but also across the funding direction. The temperature profile recorded for the individual zones is compared to a predetermined temperature profile and used to form the corresponding control signals. With the help of zone-by-zone regulation of air distribution and / or fuel transport, an improvement in the combustion process on the grate (burnout), a minimization of pollutant emissions and a reduction in the air excess is achieved, which in the prevailing opinion also leads to a reduction in the dioxin bi must lead to the incineration of waste.

The grates considered in the case of the present application include in particular the single-lane or multi-lane feed grates, in which fixed and movable grate bars alternate in each grate path. The zone subdivision is achieved here by different primary air supply. These also include single or multi-lane-level grates, wherein the grate gradations overturning and breaking up of the fuel ski CHT cause and in which each grate element determines a grate zone in which the primary air ^'jewei time Abbrandfortschritt can be adapted to. Such a zone division without gradation is also realized in the so-called burnout grates.

However, the invention can also be used with traveling grates, ^* roller grates, push-back grids, counter-rotating slide grids and the Schütte Lrosten. With the traveling grates with a rotating conveyor, the feed speed can only be regulated together for all zones, but a zone-by-zone primary air supply is possible. The invention is also directed to a device for detecting the radiation emanating from at least two spatially separated locations of a combustion process by means of a detector device, with an evaluation device downstream of the detector device and the control device downstream of the evaluation device for influencing the combustion process.

The invention has further set itself the task of making this device suitable for use on a combustion grate and to improve the combustion on the grate.

It is therefore provided according to the invention that, in the case of a combustion grate with a plurality of grate zones, the detector device detects the radiation of individual grate zones corresponding to the material bed temperature and adjusting devices for the supply of primary air and / or for the individual grate zones which are separately adjustable

Transport speed of the fuel in the material bed through individual grate zones are assigned.

In this case, the detector device can preferably have at least one thermographic or infrared camera, which detects the radiation of several rust zones at the same time.

With a thermography camera, the material bed can be detected over a large area and with the camera downstream evaluation devices, the material bed can be assigned isotherms that are either restricted to individual zones or over several zones.

In a preferred manner, two infrared cameras are provided, each of which is a side wall of the combustion chamber are assigned and capture the same bed surface. This provides redundancy and thus security of the control.

Instead of the thermographic e-camera, which covers the bed over a large area, it is also possible for the detector device to comprise a multiplicity of individual detectors, which are assigned in groups to individual rust zones and certain product bed temperature ranges or temperatures. Here, the detectors are preferably arranged transversely to the conveying direction of the grate.

Photodiodes, rod detectors and thermocouples can be used as single oil detectors.

The invention will now be explained in more detail with reference to the attached figures:

FIG. 1 shows a schematic section through a

Step feed grate with five consecutive grate zones,

FIG. 2 a view of the grate zones with two thermographic cameras arranged on the side with an isothermal distribution that is unfavorable for combustion,

FIG. 3 a view comparable to FIG. 2 with an optimal isothermal distribution for combustion and

FIG. 4 a top view comparable to FIG. 2 and ⁴ 3, however, without a thermographic e-camera, but with a group of individual detectors.

The FIG. 1 shows a furnace 1 with a step feed grate 2 as described in the applicant's brochure "Combustion technology - feed grate" (P 8303-05-13 / 1 IDG). The feed grate 2 has five combustion zones A, B, C, D and E, the zones B and C or D and E being separated from one another by a stage 3 or 4. In FIG. 1 is shown schematically that the movable grate bars of the individual zones A - E are each assigned to a Rostsch Li tten 5.

The grate slides A5 - E5 can be moved back and forth via schematically illustrated hydraulic drives A6 - E6.

The kiln, in particular MÜLL, is fed into the grate 2 via a funnel 7 and a likewise hydraulically actuated distributor 8, specifically to the feed zone 8 ".

The allocation zone 8 'and the combustion zones A - E with movable grate bars are each associated with underwind zones 9 and A9 - E9, to which primary combustion air can be supplied via control lines 9' and A12 - E12. The flue gases rising from the combustion grate 2 can still be supplied via a line 12 and control flaps 12 'and 12 "secondary air via several nozzles 13.

In the side walls 14a and 14b of the combustion chamber, two thermographic cameras 15a and 15b are arranged in such a way that they cover substantially the entire rectangular area of zones B, C and D. This can be achieved with an imaging and focusing opti, not shown, but common in the field.

On the output side, the two thermography cameras 15 are connected to an evaluation circuit 16 which, as schematically represented by the arrow S, specifies the desired temperature profile in the area of the three monitored zones B, C and D. Monitoring can also be extended to the other zones or to two adjacent or separate zones are restricted; this depends on the desired level of monitoring and regulation.

On the output side, the evaluation circuit 16 is connected to the drives A6 - E6 for the feed and the flaps A12 - E12 for the primary air supply. It is also possible that the evaluation circuit also controls the flap 9 * for the primary air zone 9, the flap 10 'for the total primary air volume, the drive of the component 8 and the caps 12 * and 12 "for the secondary air.

If it makes sense for the control, the measurement signals of the in FIG. 1 shown flow rates measuring devices 17 of the evaluation circuit 16 are switched on.

In the FIG. FIG. 2 shows a course of combustion along and transversely to the grating direction VS of the grate, which does not lead to optimal combustion. The temperature range with assumed here highest combustion temperature is too far forward, ie essentially in the zone B, and is located in the ^"zone D, an area while a lower temperature than in the hot zone, but a lower temperature should here be achieved already . The

Combustion is therefore elongated.

I.

The thermography cameras 15 record the two di ensi ona le radiation distribution in the area of zones B - D and the evaluation circuit compares the resulting isotherms according to FIG. 2 with the predetermined target isotherms, as shown in FIG. 3 are shown.

By appropriate actuation of some or all of the drive units A6-E6 for the rust zones, possibly also of the distributor 8, and one Corresponding adjustment of the primary air supply r for the combustion zones and, if appropriate, the addition zone 8 can be achieved that the combustion essentially corresponds to that shown in FIG. 3 shows the isothermal curve shown, ie ^■ the combustion process which leads to the highest isotherm 1200 C is shifted to zone C. At the same time, the second area of higher temperature in zone D is reduced. All of this leads to optimal combustion.

In the embodiment according to FIG. 4, no thermographic camera is used, but zones B, C and D are assigned individual detectors arranged in groups, each of which emits an output signal when a predetermined temperature or a predetermined temperature range prevails in its field of vision.

The grate is designed in three lanes, i. H. In the individual zones, partial zones are formed transversely to the feed direction, e.g. B. BI, BII and BIII. These sub-zones can be assigned separate feed devices and / or separate primary air feeds. Each of the sub-zones is assigned a detector assembly 17 with individual detectors 17a, 17b, 17c and 17d, each of which detects a separate temperature range.

In this embodiment, compared to the use of a thermographic camera, a certain digitization of the signals corresponding to the temperatures has already been achieved, so that the evaluation circuit 16 can be significantly simplified. In addition, such groups of detectors are also cheaper than thermography cameras. Of course, the evaluation circuit, which is connected downstream of a thermographic camera, can be designed such that individual paths are taken into account in the evaluation. Appropriately designed focusing optics can be assigned to the entire assembly 17 or the individual elements are so that the individual sub-zones z. B. BI, BII and BIII to the extent necessary, as shown in FIG. 4 is outlined.

A complete coverage of the rectangular zones or tracks is shown in the figures. But it is quite conceivable that the desired goal of an improved regulation even with a partial cover, z. B. an elliptical or circular coverage of the rectangular zones or tracks is achieved.

(4 sheets of drawings)

Claims

1. Method for detecting the radiation emanating from at least two spatially separated points in a combustion process and regulating the

Combustion process as a function of the radiation detected, characterized in that, in order to detect the radiation from a combustion on a grate, the radiation emanating essentially from individual combustion grate zones of the grate is detected and, depending on the radiation detected, the primary air supplied to the individual combustion zones and / or the transport speed of the fuel in individual zones is regulated.

2. Device for detecting the radiation emanating from at least two spatially separated points of a combustion process by means of a

Detector device, with an evaluation device downstream of the detector device and the control device downstream of the evaluation device for influencing the combustion process, characterized in that in the case of a combustion grate (2) with a plurality of grate zones (A - E), the detector device (15; 17) emits the radiation corresponding to the material bed temperature individually Rust zones detected and the individual rust zones adjustable adjusting devices (A12 - E12) for the supply of primary air and / or (A6 -E6) for the Transport speed of the fuel in the material bed through individual grate zones are assigned.

3. Apparatus according to claim 2, d a d u r c h g e k e n n z e i c h n e t that the detector device have at least one thermography or infrared camera (15a; 15b) which simultaneously detects the radiation of several rust zones.

4. Apparatus according to claim 3, d a d u r c h g e k e n n z e i c h n e t that two infrared cameras (15a, 15b) are provided, which are each associated with a side wall (14a, 14b) of the combustion chamber and capture the same good surface.

5. Apparatus according to claim 2, d a d u r c h g e k e n n z e i c h n e t that the detector device comprises a plurality of individual detectors (17a - 17d), which are assigned in groups (17) to individual grate zones (B - D; BI - BIII) and certain material bed temperature ranges or temperatures.