GB2079927A - A process for the controlled combustion of solid fossil fuel - Google Patents
A process for the controlled combustion of solid fossil fuel Download PDFInfo
- Publication number
- GB2079927A GB2079927A GB8119239A GB8119239A GB2079927A GB 2079927 A GB2079927 A GB 2079927A GB 8119239 A GB8119239 A GB 8119239A GB 8119239 A GB8119239 A GB 8119239A GB 2079927 A GB2079927 A GB 2079927A
- Authority
- GB
- United Kingdom
- Prior art keywords
- combustion
- individual
- radiation
- fuel
- burners
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000002485 combustion reaction Methods 0.000 title claims abstract description 63
- 238000000034 method Methods 0.000 title claims abstract description 20
- 239000002803 fossil fuel Substances 0.000 title claims description 6
- 239000007787 solid Substances 0.000 title claims description 6
- 230000005855 radiation Effects 0.000 claims abstract description 48
- 239000000446 fuel Substances 0.000 claims abstract description 26
- 239000002817 coal dust Substances 0.000 claims abstract description 7
- 238000012544 monitoring process Methods 0.000 claims description 2
- 238000009434 installation Methods 0.000 abstract description 12
- 239000002912 waste gas Substances 0.000 abstract description 10
- 238000005259 measurement Methods 0.000 description 15
- 239000007789 gas Substances 0.000 description 10
- 238000004458 analytical method Methods 0.000 description 5
- 238000005260 corrosion Methods 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 230000001419 dependent effect Effects 0.000 description 2
- 239000000428 dust Substances 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- 230000000007 visual effect Effects 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000001934 delay Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 238000004868 gas analysis Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000009827 uniform distribution Methods 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N1/00—Regulating fuel supply
- F23N1/02—Regulating fuel supply conjointly with air supply
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
- F23N5/02—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium
- F23N5/08—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using light-sensitive elements
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
- F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel
- F23N2005/181—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel using detectors sensitive to rate of flow of air
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2221/00—Pretreatment or prehandling
- F23N2221/08—Preheating the air
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2229/00—Flame sensors
- F23N2229/16—Flame sensors using two or more of the same types of flame sensor
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2237/00—Controlling
- F23N2237/02—Controlling two or more burners
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2239/00—Fuels
- F23N2239/02—Solid fuels
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Control Of Combustion (AREA)
Abstract
In this process the fuel, such as coal dust, and combustion air are fed to a combustion chamber 1 via individual burners 2 having single flames 3 associated therewith. The intensity of radiation of each of the flames 3 is monitored by three radiation detectors 4 of which one is allotted to the base of the flame 3, one to the main combustion zone and one to the top of the flame 3. The supply of fuel and/or combustion air to the individual burners 2 is controlled as a function of the measured intensity of radiation of the flames 3 associated with the individual burners 2. In this way variations in the quality of fuel or incorrect supply of fuel and/or combustion air can be rapidly compensated for, so that the installation does not have to be operated with an excess of air and the emission of waste gases is minimised. <IMAGE>
Description
SPECIFICATION
A process for the controlled combustion of solid fossil fuel
This invention relates to a process for the controlled combustion of solid fossil fuel, for instance coal dust, in which the fuel and combustion air are fed to a combustion chamber via individual burners. The invention also reiates to apparatus which is suitable for carrying out this process.
In coal-fired boiler installations utilising burner firing, there are usually provided for each boiler from four to eight individual burners by means of which the previously prepared fuel, for instance coal dust, and the combustion air are fed to the combustion chamber. Taking into consideration the requirements for a low emission value of the waste gases produced during the combustion process in order to protect the environment, and the overall efficiency of the installation, an essentially complete, and thus largely residue-free combustion of the fuel fed to the combustion chamber is aimed at. The principal influencing factors for the combustion process within the boiler are therefore the amount of air fed to it, the supply of fuel to the individual pulverisers which are connected to the combustion chamber, and the control of the composition of the waste gases.
Accordingly the parameters used to monitor the supply of air and fuel and/or control of the waste gas composition are also used for controlling the combustion process.
In the course of controlling the combustion by measuring the supply of air, it is known to measure the total amount of air. This measurement of the total amount of air is relatively reliable. However a correspondingly long range of measurement is required on the cold air side prior to preheating of the air, so that the combustion installation has to be relatively large.
In addition, with this method of measuring, it is not possible to determine the amounts of air present in the individual burners, so that with the measurement of the total amount of air, in particular where a large number of individual burners are provided, limits are set for the accuracy of control.
With the so-called measurement of individual amounts of air, that is the measurement of the amounts of air fed to the individual burners, it is possible to determine the distribution of amounts of air present in the individual burners, although this measurement suffers from the fact that generally the ranges of measurement which are possible are not sufficiently long. Moreover, since the flow through the individual channels leading to the burners is not high and the dust content of the air uncontrollably influences the measurement results, the measurement of individual amounts of air is relatively unreliable. Furthermore, with this method, it is not possible to determine variations in amounts during operation which are caused by wear of the guiding and controlling devices due to the amounts of dust carried along from the air heater.
Further difficulties also arise in the control of the combustion process due to the supply of fuel to the individual burners which is subject to considerable tolerances dependent on load. A uniform distribution of flow to the individual burners of the fuel fed to the boiler, which flow consists of transporting air and graded fuel, for instance coal dust, for all boiler loads, is accordingly virtually excluded by the formation of strands dependent on flow, especially during the grinding and grading process. Just as the appearance of corrosion in the conducting and controlling equipment during operation causes indeterminable variations in the amount of air being passed through, so the appearance of corrosion in the grading and separating equipment produces uncontrollabie changes in the fuel supply.In the same way the appearance of corrosion affects the distribution equipment and, as a result of temperature stress, distortion graduaily occurs in the mouthpieces of the burners. The slagging which forms on the mouthpieces of the burners is also an influencing factor in varying the amount of flow. Even if this slagging is removed at certain intervals, it soon leads to variations in the amounts of fuel and air conducted to the boiler.
In order to adhere to predetermined emission values of the waste gases, in spite of these variations which are difficult to control, and thus to minimise the unburnt residue, boiler installations are often operated with an excess of air, whereby the operating value of the burner which carries through the most fuel and the relatively smallest amount of air represents the reference variable for controlling the combustion process. It has been proved in practice that, even after constructing installations with parts which have a high resistance to corrosion by coal dust and/or with sufficient ranges of measurement for measuring individual amounts of air fed to the individual burners, the installations must be operated with an excess of air of around 1 5 to 20%, and, in the case of dry combustion which has worse combustion properties, with an excess of air of around 20 to 30%.Associated with this excess of air which is not necessary for total combustion there is corresponding emission of waste gases to that the total efficiency of these installations is unsatisfactory.
Control of the combustion process is generally effected by equipment which analyses the boiler gas by continually checking the boiler gas drawn off from one or more parts of the boiler. This checking is carried out at boiler gas temperatures of around 5000C or below in the area of the heat exchange surfaces or at the output of the boiler.
However, this method of checking suffers from substantial time delays, since the boiler gas drawn off has to be cooled, dried and filtered during analysis, so that the result of the analysis obtained is usually no longer representative for the current state of the combustion process. Apart from this, it is not possible to check the individual burners by analysis of the boiler gas since the boiler gas which is drawn off is not associated with individual burners. Therefore, with gas analysis, it is only possible to correlate the total amount of air and the total amount of fuel with the boiler gas resulting from combustion, so that in this case also operation must be carried out with an excess of air due to the varying rates of operation of the individual burners.
Finally, visual methods of measurement are
known which work on the basis of absorption of
ultraviolet, infrared or visible radiation. These
visual methods of measurement permit faster
measuring but with not such high accuracy and
are only appiicable on the final boiler heating
surfaces at boiler gas temperatures below 3000C
in refined boiler gas.
The object of the invention is to enable highly
sensitive and rapid control of the combustion
process and to substantially minimise the
emission of waste gases.
According to the invention there is provided a
process for the controlled combustion of solid
fossil fuel, for instance coal dust, wherein fuel and
combustion air are fed to a combustion chamber
via individual burners, and the combustion process
is controlled by monitoring the intensity of
radiation of the flames associated with the burners
and varying the supply of fuel and/or combustion
air to the individual burners as a function of the
intensity of radiation of the flames associated with the individual burners.
In this way variations in the quality of fuel or
incorrect or inaccurate supply of fuel and/or
combustion air can quickly be determined without
incurring great expense, and these can be
compensated for by correspondingly adjusting the
supply to the individual burner. Since reliable
control of the individual burners is possible by
means of the intensity of radiation, the installation
does not have to be operated with an excess of air,
so the emission of waste gases is minimised.
Simultaneously, the total efficiency of the
installation is improved by the accurate
adjustability. A further advantage is provided by the possibility of control of the combustion
process without time delay.
According to a particularly advantageous
embodiment, the intensity of radiation of the
individual flames is compared by measurement for
controlling the individual burners. The purpose of
this comparison is to control the supply of fuel and
combustion air in such a way that the optimum
conversion of energy for each flame is achieved.
Moreover a uniform quality of combustion of the
individual burners can be maintained, whereby
comparable combustion processes can be
obtained. Also, with a reduced excess of air, it is possible to distinguish disturbances or unreliable deviations in the combustion operation of the individual flames by comparison of the signals received by measurement of the intensity of radiation, and to correct the burners or the supply to the burners. It is appropriate for the excess of air to be minimised until the first indications of unburnt boiler gas components have been obtained by analysis of waste gases. In other respects, however, the quality of combustion of the individual flames is equal.Thus the shortcomings of the fuel are analysed and/or the distribution of air to the individual burners adjusted and, where good combustion results, the excess of air which would otherwise increase emission of waste gases is minimised.
It is appropriate for one or more radiation detectors to be associated with each burner in apparatus suitable for carrying out this process, so that the intensity of radiation in all essential areas of the individual flames can be measured and thereby a reliable picture of the operating conditions of the burner can be obtained. By this means also varying flame lengths and variations in the composition of the fuel can be allowed for.
Radiation detectors, which are also known as flame monitors, are known per sue and are used for the conversion of ultraviolet, infrared or visible radiation into electrical signals.
A very sensitive control of the combustion process can be achieved if appropriate radiation detectors for varying wavelengths are provided for each individual burner.
A good determination of the combustion quality of the individual burners can be achieved if three radiation detectors are provided for each individual burner, one of which is allotted to the base of the flame, one to the main combustion zone and one to the top of the flame, that is to the essential areas of the flame.
For the control to be adapted to a varying length of flame, as would occur for example in operating an installation under partial load, it is appropriate that at least the radiation detector which is allotted to the top of the flame is arranged to be pivotable. For the same reason the radiation detectors may be arranged in such a way that the distance between adjacent radiation detectors is variable depending on the type of radiation detector. In this connection it is extremely advantageous for corresponding radiation detectors of all the individual burners to be connected together, so that corresponding radiation detectors all have the same adjustable movement.
It is appropriate for the comparison by measurement of the intensity of radiation of the individual burners to be carried out by means of a comparison amplifier, graded measuring amplifiers being connected to the outputs of the individual radiation detectors.
In order that the invention may be more fully understood, an installation for carrying out the process according to the invention will now be described, by way of example, with reference to the accompanying drawing, in which the single figure is a diagrammatic illustration of a. section through the combustion chamber.
The combustion chamber 1 which is illustrated in the drawing is provided with a plurality of nonvariable head burners 2 arranged at a certain spacing from one another, of which, for the sake of simplicity, only the burner nozzles are shown. In the embodiment illustrated, the combustion chamber 1 has an essentially square cross-section and is provided with four burners 2 positioned at the four corners which are bevelled corners so that the positioning of the burners 2 is facilitated. The individual burners 2 which should be positioned at the corners of the combustion chamber 1 so as to be adjustable do not blow directly towards the centre of the combustion chamber 1, but in directions which are tangential to an imaginary circle, the centre of which coincides with the centre of the combustion chamber 1. This circie is shown as a dotted line in the drawing.By this positioning of the individual burners 2, mutual interference of the individual flames is substantially reduced so that the controlling process is not impaired. The individual flames produced by the burners 2 are denoted by the reference numeral 3.
Radiation detectors 4 extend through the walls of the combustion chamber 1. One or more radiation detectors, in this case three radiation detectors, are allotted to each burner 2 or each individual flame 3. The radiation detectors 4 allotted to the individual flames 3 are arranged in such a way that the radiation detectors allotted to one flame extend through one wall of the combustion chamber 1, one of the radiation detectors 4 being associated with the base of the flame immediately in front of the burner nozzle, another being associated with the main combustion zone of the flame, and the third being associated with the end of the reaction area, namely the top of the flame. By this arrangement it is guaranteed that the radiation detectors 4 associated with individual flames 3 do not suffer mutual interference, that is they are not impaired by the other flames, and also that all the areas of the flame essential to the combustion cycle are covered by a radiation detector 4, so that a reliable evaluation of the quality of combustion is made possible.
It is appropriate for the radiation detectors 4 to be arranged in a rotatabie or pivotable manner, so that the positions of the radiation detectors 4 can be very easily adapted to varying conditions, as could occur during operation with partial load due to the reduced length of flame or with a change of fuel. Corresponding radiation detectors 4 for all the individual flames 3 are connected together, so that corresponding radiation detectors 4 can be adjusted together, thus making the same movements.
Claims (11)
1. A process for the controlled combustion of solid fossil fuel, for instance coal dust, wherein fuel and combustion air are fed to a combustion chamber via individual burners, and the combustion process is controlled by monitoring the intensity of radiation of the flames associated with the burners and varying the supply of fuel and/or combustion air to the individual burners as a function of the intensity of radiation of the flames associated with the individual burners.
2. A process according to claim 1, wherein the intensity of radiation of the individual flames is collated to the control of the individual burners.
3. Apparatus for carrying out the process according to claim 1 or 2, wherein each burner is provided with one or more radiation detectors.
4. Apparatus according to claim 3, wherein each individual burner is provided with radiation detectors for various wavelengths.
5. Apparatus according to claim 3 or 4, wherein each individual burner is provided with three radiation detectors, one of which is allotted to the base of the flame, one to the main combustion zone and one to the top of the flame.
6. Apparatus according to claim 5, wherein at least the radiation detector which is allotted to the top of the flame is pivotable.
7. Apparatus according to any one of claims 3 to 6, wherein more than one radiation detector is associated with each burner, and the radiation detectors associated with each single flame are arranged in such a way that the distance between adjacent radiation detectors is variable.
8. Apparatus according to claim 7 when appended to claim 5 or 6, wherein corresponding radiation detectors for all the individual burners are connected together, so that corresponding radiation detectors all make the same adjustable movement.
9. Apparatus according to any one of claims 3 to 8, wherein the radiation detectors are connected to a comparison amplifier.
10. A process for the controlled combustion of solid fossil fuel, substantially as hereinbefore described with reference to the accompanying drawing.
11. Apparatus for carrying out the process according to claim 1, substantially as hereinbefore described with reference to the accompanying drawing.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19803024401 DE3024401A1 (en) | 1980-06-28 | 1980-06-28 | METHOD FOR CONTROLLED COMBUSTION OF SOLID FOSSIL FUELS, ESPECIALLY CARBON DUST |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2079927A true GB2079927A (en) | 1982-01-27 |
| GB2079927B GB2079927B (en) | 1984-09-12 |
Family
ID=6105780
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8119239A Expired GB2079927B (en) | 1980-06-28 | 1981-06-22 | A process for the controlled combustion of solid fossil fuel |
Country Status (3)
| Country | Link |
|---|---|
| DE (1) | DE3024401A1 (en) |
| GB (1) | GB2079927B (en) |
| ZA (1) | ZA814191B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4575333A (en) * | 1984-05-02 | 1986-03-11 | Bryant Jack A | Flame monitor time delay control |
| EP0612961A3 (en) * | 1993-02-24 | 1995-08-30 | Rwe Entsorgung Ag | Method for determining characteristic properties of processes producing radicals. |
| WO2018121968A1 (en) * | 2016-12-27 | 2018-07-05 | General Electric Technology Gmbh | System and method for combustion system control |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5944519A (en) * | 1982-09-03 | 1984-03-13 | Hitachi Ltd | Combustion condition diagnosis method |
| DE3904272C3 (en) * | 1989-02-14 | 1998-01-08 | Steinmueller Gmbh L & C | Method for detecting the radiation emanating from at least two spatially separate locations of at least one combustion zone on a grate and device for detecting such radiation |
| JP2724868B2 (en) * | 1989-03-14 | 1998-03-09 | 株式会社日立製作所 | Gas flow correction device and method |
| ATE497128T1 (en) * | 2003-10-15 | 2011-02-15 | Powitec Intelligent Tech Gmbh | METHOD FOR CONTROLLING A THERMODYNAMIC SYSTEM |
-
1980
- 1980-06-28 DE DE19803024401 patent/DE3024401A1/en not_active Withdrawn
-
1981
- 1981-06-22 ZA ZA814191A patent/ZA814191B/en unknown
- 1981-06-22 GB GB8119239A patent/GB2079927B/en not_active Expired
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4575333A (en) * | 1984-05-02 | 1986-03-11 | Bryant Jack A | Flame monitor time delay control |
| EP0612961A3 (en) * | 1993-02-24 | 1995-08-30 | Rwe Entsorgung Ag | Method for determining characteristic properties of processes producing radicals. |
| WO2018121968A1 (en) * | 2016-12-27 | 2018-07-05 | General Electric Technology Gmbh | System and method for combustion system control |
| CN110088532A (en) * | 2016-12-27 | 2019-08-02 | 通用电器技术有限公司 | System and method for combustion system control |
| JP2020528989A (en) * | 2016-12-27 | 2020-10-01 | ゼネラル エレクトリック テクノロジー ゲゼルシャフト ミット ベシュレンクテル ハフツングＧｅｎｅｒａｌ Ｅｌｅｃｔｒｉｃ Ｔｅｃｈｎｏｌｏｇｙ ＧｍｂＨ | Systems and methods for combustion system control |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2079927B (en) | 1984-09-12 |
| ZA814191B (en) | 1982-08-25 |
| DE3024401A1 (en) | 1982-01-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |