JP3916572B2 - Combustion control device for incinerator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is based on the combustion index indicating the combustion state of the dust supplied into the furnace by the dust supply means, and the amount of primary combustion air supplied below the incineration treatment zone for incinerating the waste and the amount of primary combustion air The present invention relates to a combustion control device for an incinerator that adjusts a heating temperature.
[0002]
[Prior art]
In the incinerator combustion control apparatus, as a first conventional technique, when the oxygen concentration in the exhaust gas is a normal value (during normal combustion below the upper limit concentration), the primary combustion air is heated based on the amount of heat generated by the dust. In addition to controlling the temperature, feedback control is performed to PID control the supply amount of primary combustion air based on the amount of steam generated in the boiler, and when the oxygen concentration in the exhaust gas rises above the upper limit concentration, There is one that corrects the heating temperature of the primary combustion air to a high temperature side based on the amount of increase, and limits the supply amount of the primary combustion air with an upper limit value (see Patent Document 1).
[0003]
As a second conventional technique, the dust supply efficiency (dust supply amount of the dust supply means) is estimated from the operating speed of the dust supply means for supplying dust into the furnace and the history of the amount of dust supply, and the target waste incineration amount is determined. In order to achieve this, there is one that controls the operation speed of the dust supply means based on the dust supply efficiency (see Patent Document 2). As a third conventional technique, the dust supply efficiency, the amount of heat generated by the dust, There is one that controls the operating speed of the dust supplying means based on the target heat generation amount (see Patent Document 3).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-61932 (page 2-5, FIGS. 1 to 6)
[Patent Document 2]
JP 7-269834 A (page 2-4, FIGS. 1 to 4)
[Patent Document 3]
JP 2002-349827 A (page 1-5, FIG. 1 to FIG. 2)
[0005]
[Problems to be solved by the invention]
However, in the first prior art, when the oxygen concentration is a normal value, if the heat generation amount is not a low value, and the dust that is compressed and condensed in the dust pits is supplied, the response is delayed. there were. That is, when the oxygen concentration is a normal value, no change in the amount of heat generated by the dust appears, so the heating temperature of the primary combustion air based on the amount of heat generated by the dust is not controlled, and the dust with low air permeability is supplied. This is because the control for increasing the temperature of the primary combustion air is performed only after the surface area of the dust that is in contact with the combustion air decreases, the combustion amount in the furnace decreases and the oxygen concentration increases.
The dust supply efficiency increases when the dust with low air permeability is supplied. However, the second and third prior arts have a problem with the dust with low air permeability when the dust supply efficiency increases. There is no particular description of control of the primary combustion air.
[0006]
The present invention has been made in view of the above circumstances, and an object of the present invention is to promptly respond to a decrease in the combustion amount when condensed dust having low air permeability is supplied. An object of the present invention is to provide a combustion control device for an incinerator.
[0007]
[Means for Solving the Problems]
In the invention according to claim 1 of the combustion control device of the incinerator for realizing the above object, the primary combustion air is supplied below the incineration treatment zone where the dust supplied into the furnace by the dust supplying means is incinerated. Combustion air supply means and control means for adjusting a supply amount of primary combustion air by the primary combustion air supply means based on a combustion index indicating a combustion state of dust in the furnace are provided. The means is to correct the supply amount of primary combustion air by the primary combustion air supply means to the increase side when the dust supply efficiency representing the dust supply amount of the dust supply means is increased.
[0008]
According to the above configuration, when the control unit performs control to adjust the supply amount of the primary combustion air by the primary combustion air supply unit based on the combustion index indicating the combustion state of the dust in the furnace, When the dust supply efficiency representing the dust supply amount of the dust means increases, the supply amount of the primary combustion air by the primary combustion air supply means is corrected to the increase side in the adjustment control of the air supply amount.
That is, when the dust supply efficiency is increased, the specific gravity of the dust is increased and the air permeability is predicted to be lowered, so the flow rate is increased by increasing the supply amount of primary combustion air supplied below the incineration zone, By increasing the air permeability to dust, the surface area of dust touched by oxygen can be increased, combustion can be promoted, and combustion reduction can be prevented.
Accordingly, there is provided a combustion control device for an incinerator capable of responding quickly and avoiding a decrease in combustion amount when condensed dust having low air permeability is supplied.
[0009]
A characteristic configuration of the invention according to claim 2 is the invention according to claim 1, wherein in the incineration treatment zone, a drying treatment zone, a combustion treatment zone, and a post-combustion treatment zone are sequentially arranged from the upper side along the dust conveyance direction. And the control means corrects at least one of the air supply amount for the drying treatment zone, the air supply amount for the combustion treatment zone, and the total air supply amount for all the treatment zones to the increasing side. .
[0010]
That is, when the dust supply efficiency is increased, the amount of air supplied to the drying treatment zone is increased, thereby increasing the drying speed of dust in the drying treatment zone and preventing the occurrence of combustion reduction due to a decrease in air permeability. .
Also, when the dust supply efficiency is increased, increasing the amount of air supplied to the combustion treatment zone increases the amount of dust combustion in the combustion treatment zone, promotes combustion due to an increase in radiant heat, and reduces the combustion caused by a decrease in air permeability. Can be prevented.
In addition, when the dust supply efficiency is increased, the amount of air supplied to all the treatment zones is increased, so that the drying speed of the waste is increased in the drying treatment zone, the amount of dust combustion is increased in the combustion treatment zone, and the radiant heat is increased. Combustion is promoted, and it is possible to prevent the occurrence of a decrease in combustion due to a decrease in air permeability.
Therefore, a preferred embodiment of the combustion control device for an incinerator that can avoid a decrease in the combustion amount when condensed dust with low air permeability is supplied is provided.
[0011]
In the invention which concerns on Claim 3, the primary combustion air heating means which heats the primary combustion air supplied to the lower part of the incineration processing zone which incinerates the garbage supplied in the furnace by the dust supply means, and the waste in the furnace And a control means for adjusting the heating temperature of the primary combustion air by the primary combustion air heating means based on a combustion index indicating a combustion state, and the characteristic configuration is that the control means has a dust supply amount of the dust supply means. When the dust supply efficiency representing is increased, the heating temperature of the primary combustion air by the primary combustion air heating means is corrected to the high temperature side.
[0012]
That is, when the dust supply efficiency is increased, the specific gravity of dust is increased, and a decrease in air permeability is predicted. Therefore, the heating temperature of the primary combustion air supplied below the incineration treatment zone is increased. As a result, according to Boyle Charles' law, air expands, the flow velocity increases, and the air permeability to dust is increased, thereby increasing the surface area of dust contacted with oxygen to promote combustion and preventing the occurrence of combustion deterioration. it can.
Accordingly, there is provided a combustion control device for an incinerator capable of responding quickly and avoiding a decrease in combustion amount when condensed dust having low air permeability is supplied.
[0013]
According to a fourth aspect of the present invention, in the invention according to the third aspect, the control unit detects a furnace outlet temperature as the combustion index as the adjustment control of the primary combustion air heating temperature based on the combustion index. Adjustment based on detection information of the furnace outlet temperature detecting means, when the furnace outlet temperature is low, the heating temperature of the primary combustion air is increased, and when the furnace outlet temperature is high, the heating temperature of the primary combustion air is decreased The point is to execute the control.
[0014]
As shown in the configuration of claim 3, when the dust supply efficiency is increased, the heating temperature of the primary combustion air in the adjustment control is corrected to a high temperature side. When the dust supply efficiency rises, the target value of the primary combustion air heating temperature based on the furnace outlet temperature is corrected to the high temperature side, so that the combustion promotion control corresponding to the increase in the dust supply efficiency and the furnace outlet temperature are used. The heating temperature control of the primary combustion air can be made compatible.
Therefore, a preferred embodiment of the combustion control device for an incinerator that can avoid a decrease in the combustion amount when condensed dust with low air permeability is supplied is provided.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an incinerator combustion control apparatus according to the present invention will be described below with reference to the drawings.
As shown in FIG. 1, a bucket 1 that picks up and conveys the dust accumulated in the garbage pit 20, a hopper 2 into which the garbage picked up by the bucket 1 is placed, and an incinerator 3 for removing the dust in the hopper 2. A pusher mechanism 4 as dust supplying means that reciprocates to push in and supply, a stoker-type incineration treatment zone 5 that incinerates while conveying dust supplied into the furnace by the pusher mechanism 4, and this incineration treatment An ash pit 6 for recovering incinerated ash from the belt 5, a steam turbine 8 to which steam is supplied from a waste heat boiler 7 for recovering heat generated in the furnace, and power generation driven by the steam turbine 8 The waste incineration equipment is configured so that the exhaust gas from the incinerator 3 is processed by the exhaust gas processing unit 10 having a bag filter or the like and then discharged from the chimney 11. .
[0016]
Although not shown in the drawings, the steam from the waste heat boiler 7 is heated in a steam heater disposed in a flue for sending exhaust gas from the incinerator 3 and is stored in a steam reservoir in a dry vaporized state. A steam cycle is configured such that steam from the steam reservoir is supplied to the steam turbine 8 to drive the generator 9, and then condensate and finally return to the waste heat boiler 7.
[0017]
The incineration zone 5 includes a drying zone 5a that dries the supplied dust from the upper side (the pusher mechanism 4 side) along the direction of dust transport in the furnace and heats it to near the ignition point. A combustion treatment zone 5b for burning garbage and a post-combustion treatment zone 5c for ashing the burned waste are sequentially arranged. Each of the treatment zones 5a, 5b, and 5c is formed in a staircase shape so that the incineration treatment zone 5 has a lower level toward the lower side in the transport direction.
[0018]
Each processing zone 5a, 5b, 5c has a fixed grate in a fixed state and a movable grate slidable with respect to the fixed grate, and the movable grate is fixed by operation of a hydraulic cylinder (not shown). The dust on the incineration zone is slid back and forth with respect to the grate, and the dust is agitated while being sequentially transferred in the directions of the drying zone 5a, the combustion zone 5b, and the post-burn zone 5c. The dust ashed in the post-combustion treatment zone 5 c falls on the site of the ash pushing mechanism 12 and is conveyed and accumulated in the ash pit 6 by the ash removal conveyor 13.
[0019]
Next, primary combustion air supply means A for supplying primary combustion air below the incineration treatment zone 5 and primary combustion air heating means B for heating primary combustion air supplied below the incineration treatment zone 5 are provided. Is provided. This will be specifically described below.
[0020]
A main flow path 16 that allows air sent from the blower 15 to flow to the air preheater 14, and a bypass flow path that branches from the upstream side of the main flow path 16 and sends air to join the downstream portion of the air preheater 14. 17, a main damper 18 that controls the amount of air flowing through the main flow path 16, and a sub-damper 19 that controls the amount of air flowing through the bypass flow path 17, and a main flow downstream of the air preheater 14. A main temperature sensor Tm including a thermistor and a thermocouple for measuring the temperature of the air flowing through the passage 16 is provided. Note that a steam supply system is configured to heat the air by sending the steam stored in the steam reservoir to the air preheater 14.
[0021]
Depending on the opening of the main damper 18 and the opening of the sub-damper 19, the mixing ratio between the air sent through the main flow path 16 and heated by the air preheater 14 and the normal temperature air sent through the bypass flow path 17. The temperature of the mixed air can be adjusted by this mixing ratio. Therefore, the primary combustion air heating means B is constituted by the main flow path 16, the bypass flow path 17, the main damper 18, the auxiliary damper 19, and the like.
[0022]
The first flow path 21 is connected to the downstream side of the confluence of the main flow path 16 and the bypass flow path 17, and the first flow path 21 is disposed below the processing zones 5a, 5b, and 5c on the downstream side. A plurality of distribution paths 22 for guiding air to a plurality of wind boxes 23 are branched, and a flow rate sensor F1 that measures the flow rate of air to each distribution path 22 and a branch damper D1 that controls the flow rate of air are provided. ing. The air supplied to each distribution path 22 promotes the combustion of dust by passing upward from the wind box 23 through the treatment zones 5a, 5b, and 5c. Therefore, the first combustion air supply means A is constituted by the first flow path 21, the plurality of distribution paths 22, the plurality of wind boxes 23, the plurality of branch dampers D1, and the like.
[0023]
Although not specifically shown in the drawing, the main damper 18, the sub damper 19, and the plurality of branch dampers D1 can be set to any opening degree by the driving force of the hydraulic cylinder or the electric motor, respectively, and the air volume can be adjusted. It is configured. The flow rate sensor F1 is configured to output the flow rate of air within a unit time as an electrical signal by using an impeller type, a vortex type, or a Pitot type.
[0024]
Note that secondary combustion air supply means for supplying secondary combustion air to the interior of the furnace above the incineration treatment zone 5 in order to cause secondary combustion of the combustion gas generated with combustion of garbage in the incinerator 3. 27 is provided. An oxygen concentration sensor 26 for detecting the oxygen concentration in the exhaust gas after the secondary combustion is installed in the flue of the exhaust gas from the incinerator 3.
[0025]
A gas temperature sensor 25 such as a thermocouple for measuring the exhaust gas temperature at the furnace outlet position of the incinerator 3, that is, the furnace outlet temperature, is provided. And, if the combustion state of dust in the furnace is good, the exhaust gas temperature is an appropriate value, but if the combustion state of dust in the furnace deteriorates and the combustion amount decreases, the exhaust gas temperature decreases. The gas temperature sensor 25 constitutes a furnace outlet temperature detecting means for detecting the furnace outlet temperature as a combustion index indicating the combustion state of dust in the furnace.
[0026]
As shown in FIG. 2, a control device 30 composed of a microprocessor, a semiconductor memory, and the like is provided. The control device 30 includes the main temperature sensor Tm, a plurality of flow rate sensors F1, a gas temperature sensor 25, and an oxygen concentration sensor. 26 and each detection information of the weight sensor 24 (see FIG. 1) for detecting the weight of the dust that is picked up by the bucket 1 and put into the furnace. On the other hand, the control device 30 outputs drive signals for the bucket 1, the pusher mechanism 4, the main damper 18, the sub damper 19, the plurality of branch dampers D1, and the like.
[0027]
In the control device 30, dust supply efficiency calculating means D for calculating the dust supply efficiency representing the dust supply amount of the pusher mechanism 4 is configured. The dust supply efficiency is estimated from the operating speed of the pusher mechanism 4 and the actual value of the amount of dust input. Specifically, assuming a certain amount of dust that stays from the hopper 2 to the combustion treatment zone 5 and is expected to enter the drying and combustion process in the future, the pusher at a predetermined time required to input the amount of dust is assumed. The dust input efficiency (ton / cycle) is obtained by dividing the input weight (ton / hour) of dust by the mechanism 4 by the moving average value of the operating speed (cycle / hour) of the pusher mechanism 4 at the same predetermined time. . Details are described in Patent Document 2 and Patent Document 3 described above.
[0028]
Further, in the control device 30, an air amount adjustment control for adjusting a supply amount of primary combustion air by the primary combustion air supply means A based on a combustion index indicating a combustion state of dust in the furnace, and dust in the furnace The control means C which performs the temperature adjustment control which adjusts the heating temperature of the primary combustion air by the said primary combustion air heating means B based on the combustion parameter | index which shows this combustion state is comprised.
[0029]
Specifically, as shown in the solid line of the graph of FIG. 3, the air amount adjustment control is performed by the control unit C as a reference based on the amount of dust heat (kJ / kg) estimated by the material balance / heat balance. Calculate the amount of combustion air and make corrections based on the amount of steam (the amount of steam generated from the waste heat boiler 7), the furnace outlet temperature, the burnout point (the burnout point of garbage on the combustion treatment zone 5b), etc. Set the target value of the supply amount of combustion air.
Specifically, the temperature adjustment control is performed as shown in the solid line graph of FIG. 4, in which the control means C performs the gas temperature sensor as the adjustment control of the primary combustion air heating temperature based on the combustion index. 25, when the furnace outlet temperature is low, the heating temperature (target value) of the primary combustion air is increased, and when the furnace outlet temperature is high, the heating temperature (target value) of the primary combustion air. The adjustment control for lowering the value is executed.
[0030]
Then, as indicated by the phantom line in the graph of FIG. 3, when the dust supply efficiency (ton / cycle) is increased, the control means C performs a primary operation by the primary combustion air supply means A in the air amount adjustment control. The target value of the supply amount of combustion air is corrected to the increase side. That is, as shown in FIG. 5, the target value of the total air supply amount for all the treatment zones 5a, 5b, 5c of the combustion treatment zone 5 is corrected to the increase side. Specifically, when the dust supply efficiency increases and exceeds the set value Kt, the target value of the total air supply amount is increased by, for example, about 10% (that is, the correction rate (%) is set to 10%).
[0031]
As indicated by the phantom line in the graph of FIG. 4, the control means C performs primary combustion by the primary combustion air heating means B in the temperature adjustment control when the dust supply efficiency (ton / cycle) increases. The target value of the air heating temperature is corrected to the high temperature side. Specifically, as shown in FIG. 6, when the dust supply efficiency increases and exceeds a set value Kt, the heating temperature (target value) of the primary combustion air is increased.
5 and 6 show an example (a) in which the correction amount with respect to the target value of the air supply amount and the heating temperature is rapidly changed with respect to a change in the dust supply efficiency, and an example (b) in which the correction amount is smoothly changed. However, other characteristics may be set.
[0032]
[Another embodiment]
In the above embodiment, when the control means C increases the dust supply efficiency (ton / cycle), the supply amount of the primary combustion air by the primary combustion air supply means A in the air amount adjustment control is increased. For correction, the total air supply amount for all the treatment zones 5a, 5b, 5c of the combustion treatment zone 5 is corrected to the increase side, but this is not a limitation, and the air for the drying treatment zone 5a is not limited to this. The configuration may be such that at least one of the supply amount, the air supply amount for the combustion treatment zone 5b, and the total air supply amount for all the treatment zones 5a, 5b, 5c is corrected to the increasing side.
[0033]
Moreover, in the said embodiment, in the said temperature adjustment control, the detection information of the furnace exit temperature detection means 25 which detects a furnace exit temperature (exhaust gas temperature from a furnace) is used as a combustion parameter | index which shows the combustion state of the garbage in a furnace. However, in addition to this, for example, detection information of the amount of steam generated from the waste heat boiler 7, image information of a TV camera that detects a burnout point on the combustion treatment zone 5b, Detection information for the amount of heat generated from dust may be used as the combustion index.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the overall configuration of a garbage incinerator. FIG. 2 is a block circuit diagram of a control system. FIG. 3 is a graph showing adjustment control characteristics of a combustion air supply amount. Graph showing characteristics [Fig. 5] Graph showing correction control characteristics of combustion air supply amount [Figure 6] Graph showing correction control characteristics of combustion air heating temperature [Explanation of symbols]
3 Incinerator 4 Dust supply means 5 Incineration treatment zone 5a Drying treatment zone 5b Combustion treatment zone 5c Post-combustion treatment zone 25 Furnace outlet temperature detection means A Primary combustion air supply means B Primary combustion air heating means C Control means

Claims (4)

Primary combustion air supply means for supplying primary combustion air below an incineration treatment zone for incinerating waste supplied into the furnace by dust supply means, and the primary based on a combustion index indicating a combustion state of garbage in the furnace Control means for adjusting the amount of primary combustion air supplied by the combustion air supply means,
A combustion control apparatus for an incinerator, wherein the control means corrects the supply amount of primary combustion air by the primary combustion air supply means to the increasing side when the dust supply efficiency representing the dust supply amount of the dust supply means increases. In the incineration treatment zone, a drying treatment zone, a combustion treatment zone, and a post-combustion treatment zone are sequentially arranged from the upper side along the dust conveyance direction,
The said control means correct | amends at least 1 to the increase side among the air supply amount with respect to the said drying process zone, the air supply amount with respect to the said combustion process zone, and the total air supply amount with respect to all the process zones. Combustion control device for incinerators. Based on the primary combustion air heating means for heating the primary combustion air supplied below the incineration treatment zone for incinerating the waste supplied into the furnace by the dust supply means, and the combustion index indicating the combustion state of the waste in the furnace Control means for adjusting the heating temperature of the primary combustion air by the primary combustion air heating means,
A combustion control apparatus for an incinerator, wherein the control means corrects the heating temperature of the primary combustion air by the primary combustion air heating means to a high temperature side when dust supply efficiency representing the amount of dust supplied by the dust supply means increases. When the control means controls the primary combustion air heating temperature based on the combustion index, the furnace outlet temperature is low based on detection information of the furnace outlet temperature detection means that detects the furnace outlet temperature as the combustion index. The combustion control device for an incinerator according to claim 3, wherein adjustment control is executed to increase the heating temperature of the primary combustion air and to lower the heating temperature of the primary combustion air when the furnace outlet temperature is high.

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