JP6251329B1 - Waste incinerator - Google Patents

Abstract

In a waste incinerator configured to discharge exhaust gas from a waste incinerator 1 to an exhaust passage 11, and to discharge the exhaust gas from a chimney 5 to the atmosphere via a cooling device 2 and a dust collector 3 disposed in the exhaust passage 11. It is possible to promote stable complete combustion in the waste incinerator 1. A waste incinerator supplies secondary combustion air supply means for supplying secondary combustion air to a waste incinerator, and supplies exhaust gas discharged from the waste incinerator to the secondary combustion air supply means. Exhaust gas recirculation means 8 for mixing with the secondary combustion air, and a control device 10 for controlling the operation of each means 7, 8. The control device 10 controls the mixing ratio of the secondary combustion air and the exhaust gas so as to keep the oxygen concentration within a predetermined target range based on the detection output of the oxygen concentration in the waste incinerator 1 and the secondary combustion. Control is performed so that the supply flow rate of the mixture of air and exhaust gas to the waste incinerator 1 is kept constant. [Selection] Figure 1

Description

  The present invention relates to a waste incinerator having a configuration in which exhaust gas discharged from a waste incinerator is mixed with secondary combustion air and recirculated to the waste incinerator.

  For example, in Patent Document 1, a means for supplying primary combustion air to an incinerator, a secondary combustion air supply means for supplying secondary combustion air to an incinerator, and an exhaust pipe from the incinerator to a chimney are used for the incinerator. A boiler that is arranged downstream and recovers heat to cool the exhaust gas, a dust collector for purifying the exhaust gas cooled by the boiler, and only the exhaust gas that has passed through the dust collector is passed to the incinerator. Refluxing means for refluxing.

  The secondary combustion air supply means includes a mixed gas supply pipe connecting the atmosphere and the incinerator, a secondary blower installed in the mixed gas supply pipe, and an upstream of the secondary blower in the mixed gas supply pipe. And an exhaust gas supply pipe connecting the downstream side of the dust collector in the exhaust pipe, an exhaust gas damper disposed in the exhaust gas supply pipe, and a secondary combustion air flow rate control device.

  In this secondary combustion air flow rate control device, the oxygen concentration downstream of the dust collector is detected by an oxygen concentration detection control device, and the mixing amount of the exhaust gas and secondary combustion air is determined based on the detection result. In addition, the blowing amount of the mixed gas of the exhaust gas and the secondary combustion air is controlled to be constant.

Japanese Patent No. 3438861

  In Patent Document 1, when the mixed gas of the exhaust gas and the secondary combustion air is supplied to the incinerator by the secondary combustion air supply means, it is determined based on the oxygen concentration downstream of the dust collector. Therefore, it can be said that the responsiveness for keeping the oxygen concentration in the incinerator within the target range which is an index of the oxygen concentration for complete combustion is poor. There is room for improvement here.

  In view of such circumstances, the present invention is a waste incinerator having a configuration in which exhaust gas discharged from a waste incinerator is mixed with secondary combustion air and recirculated to the waste incinerator. The purpose is to enable complete combustion.

The present invention is a waste incinerator configured to release exhaust gas from a waste incinerator to an exhaust passage, and to release the exhaust gas from a chimney to the atmosphere via a cooling device and a dust collector disposed in the exhaust passage, Primary combustion air supply means for supplying primary combustion air to a waste incinerator; secondary combustion air supply means for supplying secondary combustion air to the waste incinerator; and exhaust gas discharged from the waste incinerator for the secondary Exhaust gas recirculation means for supplying to the combustion air supply means and mixing with the secondary combustion air, and cooling air in the waste incinerator at a position closer to the exhaust outlet of the waste incinerator than the supply position of the secondary combustion air wherein a cooling air supply means for supplying, to said control unit for controlling the operation of each unit, wherein the control device, the exhaust of the waste incinerator than the supply position of the secondary combustion air in the waste incinerator Said secondary combustion air to accommodate the oxygen concentration within a predetermined target range based on the detection output from the oxygen concentration-detecting means for detecting an oxygen concentration at a position upstream of the supply position of the deviation a and the cooling air In addition to controlling the mixing ratio of the exhaust gas to the waste incinerator, the mixture flow of the secondary combustion air and the exhaust gas is controlled so as to keep the supply flow rate to the waste incinerator constant . The supply amount of the cooling air by the cooling air supply means is controlled so as to keep the furnace temperature constant based on the detection output from the furnace temperature detection means for detecting the temperature .

  In this configuration, since the exhaust gas is mixed with the secondary combustion air and supplied to the waste incinerator, the amount of exhaust gas discharged to the atmosphere can be reduced.

  Further, since the oxygen concentration in the waste incinerator is detected and the mixing ratio of the secondary combustion air and the exhaust gas is controlled so that the oxygen concentration falls within a predetermined target range, the waste incineration Even when the oxygen concentration in the refuse incinerator is likely to decrease as in the case of rapid combustion operation of the furnace, the oxygen concentration can be maintained at a predetermined target value with better response than the above-mentioned Patent Document 1. become.

  Furthermore, since the supply flow rate of the air-fuel mixture to the waste incinerator is controlled to be constant, the amount of oxygen required for combustion is reduced as in the low load operation of the waste incinerator. However, the stirring effect in the waste incinerator can be kept constant.

  Thereby, according to this invention, the stable complete combustion in the said waste incinerator can be promoted irrespective of the fluctuation | variation of the combustion operation of the said waste incinerator.

Furthermore, in this configuration, the temperature control in the waste incinerator is performed separately from the combustion control in the secondary combustion air, so that stable complete combustion in the waste incinerator is promoted, It is possible to achieve both furnace temperature control.

  The secondary combustion air supply means includes an air-fuel mixture supply path communicating the refuse incinerator and the atmosphere, and a secondary combustion air blower for sucking the air as secondary combustion air into the air-fuel mixture supply path; A flow rate detecting means for detecting a gas flow rate downstream of the secondary combustion air blower in the mixture supply path, and the exhaust gas recirculation means is connected to the downstream side of the dust collector in the exhaust path. It is preferable to include an exhaust gas recirculation path that connects the upstream side of the secondary combustion air blower in the air supply path and a damper that adjusts the flow rate of the exhaust gas that passes through the exhaust gas recirculation path.

  Here, the configurations of the secondary combustion air supply means and the exhaust gas recirculation means are specified, and the embodiment can be realized by this specification.

  Further, the control device controls the opening degree of the damper and the secondary combustion air based on the detection output of the oxygen concentration detection means for detecting the oxygen concentration in the refuse incinerator and the detection output of the flow rate detection means. It is preferable that the air-fuel mixture in which the secondary combustion air and the exhaust gas are mixed at a predetermined ratio is supplied from the air-fuel mixture supply path to the waste incinerator by executing rotation control of the blower. . Here, the control target by the control device is specified.

  Further, the control device is configured to set the detected value of the oxygen concentration in the waste incinerator within the target range based on a detection output from an oxygen concentration detection unit that detects an oxygen concentration in the waste incinerator. A first calculation process for calculating an opening degree control amount of the damper, a first execution process for controlling the operation of the damper based on the opening degree control amount calculated in the first calculation process; Second calculation processing for calculating a rotation control amount of the secondary combustion air blower so as to keep a supply flow rate of the air-fuel mixture of the secondary combustion air and the exhaust gas supplied to the waste incinerator based on the detection output And a second execution process for controlling the operation of the secondary combustion air blower based on the rotation control amount calculated in the second calculation process. Here, the process executed by the control device, that is, the control program executed by the control device is specified.

  The oxygen concentration detection means is preferably a laser analyzer and is installed in a horizontal direction so as to pass through the center of the waste incinerator.

  According to the waste incinerator according to the present invention, it is possible to promote stable complete combustion in the waste incinerator.

It is a figure which shows typically the structure of one Embodiment of the waste incinerator which concerns on this invention.

  BEST MODE FOR CARRYING OUT THE INVENTION Best modes for carrying out the present invention will be described in detail below with reference to the accompanying drawings.

  FIG. 1 shows an embodiment of the present invention. The waste incinerator exhaust gas treatment facility in the illustrated example includes a waste incinerator 1, a cooling device 2, a filtering dust collector 3 such as a bag filter, an induction fan 4, a chimney 5, a primary combustion air supply means 6, and a secondary combustion. Air supply means 7, exhaust gas recirculation means 8, cooling air supply means 9, control device 10 and the like are provided.

  The garbage incinerator 1 burns garbage such as general waste, industrial waste, and infectious medical waste put in a predetermined package, for example, and the type of the incinerator is not limited.

  Although the cooling device 2 is not shown in detail, the boiler 2a that lowers the high-temperature exhaust gas discharged from the waste incinerator 1 to, for example, about 220 ° C., or the exhaust gas cooled by the cooling device 2 is further approximately 200 ° C. or less. A gas cooling chamber 2b for reducing the temperature is provided.

  The dust collector 3 neutralizes, filters, and purifies dust and harmful gas components in the exhaust gas reduced in temperature by the cooling device 2.

  The induction ventilator 4 sucks the exhaust gas in the dust collector 3 and releases it from the chimney 5 to the atmosphere.

  The primary combustion air supply means 6 supplies primary combustion air to the incineration ash discharge port 1a of the waste incinerator 1, and includes a primary combustion air supply path 6a, a primary combustion air blower 6b, and the like.

  The secondary combustion air supply means 7 supplies secondary combustion air into the waste incinerator 1, and includes an air-fuel mixture supply path 7a, a secondary combustion air blower 7b, and the like. In this embodiment, the supply position of the air-fuel mixture from the air-fuel mixture supply path 7a into the refuse incinerator 1 is set closer to the flame layer 1b than the detection position of the oxygen concentration detection means 21 described below.

  The air-fuel mixture supply path 7a communicates the waste incinerator 1 with the atmosphere. The secondary combustion air blower 7b sucks the atmosphere and the exhaust gas discharged from the waste incinerator 1 into the mixture supply path 7a as secondary combustion air.

  The exhaust gas recirculation means 8 supplies the exhaust gas discharged from the waste incinerator 1 to the secondary combustion air supply means 7 and mixes it with the secondary combustion air, and includes an exhaust gas recirculation path 8a, a damper 8b, and the like. Yes.

  The exhaust gas recirculation path 8a connects the downstream side of the dust collector 3 in the exhaust path 11 and the upstream side of the secondary combustion air blower 7b in the mixture supply path 7a. The damper 8b adjusts the flow rate of the exhaust gas that passes through the exhaust gas recirculation path 8a.

  The cooling air supply means 9 supplies cooling air into the waste incinerator 1, and includes a cooling air supply path 9a, a cooling air blower 9b, a damper 9c, and the like. In this embodiment, the supply position of the cooling air from the cooling air supply path 9a to the waste incinerator 1 is closer to the exhaust port 1c than the supply position of the air-fuel mixture from the mixture supply path 7a to the waste incinerator 1. Is set to

  The cooling air supply path 9a communicates the waste incinerator 1 with the atmosphere. The cooling air blower 9b sucks the atmosphere as cooling air into the cooling air supply path 9a. The damper 9c adjusts the flow rate of the atmosphere passing through the cooling air supply path 9a.

  The control device 10 controls the operation of each of the means 6 to 9, and executes at least complete combustion acceleration control and furnace temperature control.

  The complete combustion promotion control is performed so that the oxygen concentration in the waste incinerator 1 falls within a predetermined target range based on the detection output from the oxygen concentration detection means 21 that detects the oxygen concentration in the waste incinerator 1, for example. While controlling the mixing ratio of the secondary combustion air and the exhaust gas, the incinerator 1 for the mixture of the secondary combustion air and the exhaust gas based on the detection output of the flow rate detection means 22 installed in the mixture supply path 7a. To keep the supply flow rate to constant.

  In this embodiment, the oxygen concentration detection means 21 is set to detect the oxygen concentration at a position closer to the exhaust port 1c than the supply position of the air-fuel mixture from the air-fuel mixture supply path 7a into the waste incinerator 1. ing.

  The oxygen concentration detection means 21 is preferably a laser analyzer. Specifically, the oxygen concentration detection means 21 is preferably installed in a horizontal direction so as to pass through the center of the cylindrical waste incinerator 1. Since this laser analyzer shows the average value of the portion through which the emitted laser penetrates, it becomes possible to detect the oxygen concentration at the desired position in the waste incinerator 1.

  The flow rate detecting means 22 detects the gas flow rate on the downstream side of the secondary combustion air blower 7b in the mixture supply path 7a.

  The in-furnace temperature control is based on the detection output from the in-furnace temperature detecting means 23 for detecting the in-furnace temperature of the waste incinerator 1 and the cooling air supply means so as to keep the in-furnace temperature of the incinerator 1 constant. 9 controls the amount of cooling air supplied.

  The in-furnace temperature detection means 23 detects the temperature in the waste incinerator 1 at a position closer to the exhaust port 1c than the cooling air supply position from the cooling air supply means 9.

  Next, the operation of the waste incinerator according to this embodiment will be described.

  During the waste incineration operation, first, the opening degree control of the damper 8b of the exhaust gas recirculation means 8 for keeping the detected value of the oxygen concentration in the waste incinerator 1 within the target range based on the detection output from the oxygen concentration detection means 21. The amount is calculated (first calculation process). The target range is set to a value (for example, 2 to 4%) serving as an index that enables complete combustion in the waste incinerator 1.

  Specifically, in the first calculation process, it is determined whether or not the detected value exceeds an upper limit value of the target range. If the detected value exceeds the upper limit value, a deviation value between the detected value and the upper limit value is determined. And the opening control amount of the damper 8b of the exhaust gas recirculation means 8 is calculated, and the process proceeds to the first execution process described below. On the other hand, if the detected value is less than or equal to the upper limit value, the detected value falls within the target range. It is determined whether the detected value is less than the lower limit value, and when the detected value is less than the lower limit value, a deviation value between the detected value and the lower limit value is calculated, and the opening degree of the damper 8b of the exhaust gas recirculation means 8 is calculated. The control amount is calculated, and the process proceeds to the first execution process described below.

  In the first execution process, the operation of the damper 8b of the exhaust gas recirculation means 8 is controlled based on the opening control amount calculated in the first calculation process.

  Thereafter, the secondary combustion air supply means 7 keeps the supply flow rate of the mixture of the secondary combustion air and the exhaust gas supplied to the waste incinerator 1 based on the detection output from the flow rate detection means 22 constant. A rotation control amount of the secondary combustion air blower 7b is calculated (second calculation process).

  The operation of the secondary combustion air blower 7b of the secondary combustion air supply means 7 is continuously controlled based on the rotation control amount calculated in the second calculation process (second execution process).

  As described above, according to the embodiment to which the present invention is applied, the exhaust gas that has passed through the dust collector 3 is mixed with the secondary combustion air and supplied to the waste incinerator 1.

That is, since the exhaust gas is reburned, the exhaust gas purification action is improved. In addition to them, because they were mixed with the exhaust gas in the secondary combustion air supplied to refuse incinerator 1, the oxygen concentration is lowered as compared with the case of supplying only secondary combustion air into the refuse incinerator 1. Therefore, it becomes possible to delay the combustion rate in the waste incinerator 1 and suppress the rise in flame temperature, so that the generation of NOx (for example, thermal NOx, fuel NOx, etc.) is suppressed. Is possible.

  By these synergistic actions, the exhaust gas discharged into the atmosphere can be cleaned as much as possible. Incidentally, it becomes possible to secure the oxygen concentration on the downstream side of the dust collector 3 to 4% or more and prevent the peak of carbon monoxide.

  Further, since the oxygen concentration in the waste incinerator 1 is detected and the mixing ratio of the secondary combustion air and the exhaust gas is controlled so that the oxygen concentration falls within a predetermined target range, the waste incinerator 1 Even when the oxygen concentration in the waste incinerator 1 is likely to decrease as in the case of rapid combustion operation, the oxygen concentration can be maintained at a predetermined target value with better response than the above-mentioned Patent Document 1. .

  Furthermore, since the supply flow rate of the air-fuel mixture to the waste incinerator 1 is controlled to be constant, even if the in-furnace temperature is lowered as in the low load operation of the waste incinerator 1 The stirring effect in the incinerator 1 can be kept constant.

  Thereby, according to the embodiment to which the present invention is applied, stable complete combustion in the waste incinerator 1 can be promoted regardless of fluctuations in the combustion operation of the waste incinerator 1. This is also advantageous for purifying exhaust gas discharged to the atmosphere.

  Further, in this embodiment, the temperature control in the waste incinerator 1 is performed separately from the combustion control in the secondary combustion air, so that stable complete combustion in the waste incinerator 1 is promoted, It becomes possible to achieve both temperature control.

  Furthermore, in this embodiment, as shown in the above-mentioned Patent Document 1, “means for recirculating only the exhaust gas to the incinerator (separate from the means for supplying the mixture of secondary combustion air and exhaust gas to the incinerator)” Therefore, it is advantageous in reducing the equipment cost as compared with Patent Document 1 described above.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used for a waste incinerator having a configuration in which exhaust gas discharged from a waste incinerator is mixed with secondary combustion air and recirculated to the waste incinerator.

1 Waste incinerator
1a Incineration ash outlet
1b Flame layer
1c Exhaust port
2 Cooling device
2a boiler
2b Gas cooling chamber
3 Dust collector
6 Primary combustion air supply means
6a Primary combustion air supply path
6b Primary combustion air blower
7 Secondary combustion air supply means
7a Mixture supply path
7b Secondary combustion air blower
8 Exhaust gas recirculation means
8a Exhaust gas recirculation path
8b damper
9 Cooling air supply means
9a Cooling air supply path
9b Cooling air blower
9c Damper 10 Control device 11 Exhaust path 21 Oxygen concentration detection means 22 Flow rate detection means 23 Furnace temperature detection means

Claims (5)

A waste incinerator configured to discharge exhaust gas from a waste incinerator to an exhaust path, and discharge the exhaust gas from a chimney to the atmosphere via a cooling device and a dust collector disposed in the exhaust path,
Primary combustion air supply means for supplying primary combustion air to the waste incinerator, secondary combustion air supply means for supplying secondary combustion air to the waste incinerator, and exhaust gas discharged from the waste incinerator Exhaust gas recirculation means for supplying the secondary combustion air to the secondary combustion air and mixing it with the secondary combustion air, and cooling air in the waste incinerator at a position closer to the exhaust outlet of the waste incinerator than the supply position of the secondary combustion air Cooling air supply means for supplying air, and a control device for controlling the operation of each means,
The control device detects an oxygen concentration at a position closer to an exhaust port of the waste incinerator than the supply position of the secondary combustion air and upstream of the cooling air supply position in the waste incinerator. Based on the detection output from the detection means , the mixing ratio of the secondary combustion air and the exhaust gas is controlled so that the oxygen concentration falls within a predetermined target range, and the mixing of the secondary combustion air and the exhaust gas is performed. In addition to controlling the supply flow rate of the gas to the waste incinerator to be constant, the in-furnace temperature is made constant based on the detection output from the in-furnace temperature detecting means for detecting the in-furnace temperature of the waste incinerator. A refuse incinerator characterized by controlling the amount of cooling air supplied by the cooling air supply means so as to maintain . In the waste incinerator according to claim 1,
The secondary combustion air supply means includes a mixture supply path that communicates the waste incinerator and the atmosphere, a secondary combustion air blower for sucking the atmosphere as secondary combustion air into the mixture supply path, and A flow rate detecting means for detecting a gas flow rate downstream of the secondary combustion air blower in the air-fuel mixture supply path,
The exhaust gas recirculation means passes through the exhaust gas recirculation passage connecting the downstream side of the dust collector in the exhaust passage and the upstream side of the secondary combustion air blower in the mixture supply passage, and the exhaust gas recirculation passage. Ru and a damper for adjusting the exhaust gas flow rate, incineration and wherein the. The waste incinerator according to claim 2 ,
The controller is
Based on the detection output of the oxygen concentration detection means for detecting the oxygen concentration in the waste incinerator and the detection output of the flow rate detection means, the opening degree control of the damper and the rotation control of the secondary combustion air blower are executed. by, supplying a mixed gas obtained by mixing the secondary combustion air and the exhaust gas at a predetermined ratio to said incinerator from the mixture supply passage, incineration and wherein the. The waste incinerator according to claim 2 ,
The controller is
Based on the detection output from the oxygen concentration detection means for detecting the oxygen concentration in the waste incinerator, the opening degree control amount of the damper for keeping the detected value of the oxygen concentration in the waste incinerator within the target range A first calculation process to calculate;
A first execution process for controlling the operation of the damper based on the opening degree control amount calculated in the first calculation process;
Based on the detection output from the flow rate detection means, the rotation control amount of the secondary combustion air blower is set so as to keep the supply flow rate of the mixture of the secondary combustion air and the exhaust gas supplied to the waste incinerator constant. A second calculation process for calculating;
The second execution processing for controlling the operation of the secondary combustion air blower on the basis of the second said rotating control amount calculated in calculation processing, waste incinerator, characterized by the execution. The refuse incineration apparatus according to claim 3 or 4 ,
The waste incinerator, wherein the oxygen concentration detection means is a laser analyzer and is installed in a horizontal direction so as to pass through the center of the waste incinerator.

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