JP2021071238A - Incineration plant and combustion controlling method thereof - Google Patents

Abstract

To stabilize steam amount generated from a boiler, in an incineration plant equipped with a garbage incinerator having plural stages of stokers including a combustion stoker, and the boiler generating steam using the heat of exhaust gas in the incinerator.SOLUTION: An amount of steam generated by a boiler is obtained, combustion adjusting gas according to the steam amount is supplied to an area below a slow combustion area regulated in at least a part of a combustion stoker, and primary combustion air is supplied to an area below plural stages of stokers other than the slow combustion area. The combustion adjusting gas when the amount of steam is a predetermined target steam amount or more is low oxygen gas with lower oxygen concentration than the primary combustion air, and the combustion adjusting gas when the steam amount does not satisfy the target steam amount is gas with higher oxygen concentration than the low oxygen gas.SELECTED DRAWING: Figure 6

Description

The present invention relates to a combustion control technique for an incinerator including a stoker-type incinerator.

Conventionally, a stoker-type incinerator has been used to incinerate waste such as municipal waste and industrial waste. Generally, in the combustion chamber of a stalker type incinerator, a dry stalker that defines a dry zone for drying water contained in waste, a combustion stalker that defines a combustion zone for volatilizing and burning volatile components of waste, and a carbon content are used. A post-combustion stoker is provided to define the post-combustion zone for complete combustion. Combustion air is supplied from the air box provided at the bottom of each stoker to the combustion chamber through the stoker, and the waste is incinerated while being transported by the stoker. Patent Documents 1 and 2 disclose such a stoker-type incinerator.

The stoker type incinerator described in Patent Document 1 is an intermediate flow type stoker type incinerator, in which a drying stoker, a combustion stoker, and a post-combustion stoker are provided in a primary combustion chamber, and above the combustion stoker and the post-combustion stoker. An entrance to the secondary combustion chamber is provided.

The stoker type incinerator described in Patent Document 2 is a parallel flow type stoker type incinerator, in which a drying stoker, a combustion stoker, and a post-combustion stoker are provided in the main combustion chamber, and above the downstream portion of the post-combustion stoker. There is an entrance to the reburning chamber. In such a parallel flow type stoker type incinerator, combustion gas and waste flow in parallel in the main combustion chamber.

An incinerator is known that includes a stoker-type incinerator as described above, a boiler that uses the heat of the exhaust gas from the incinerator to generate steam, and a power generation device that uses the steam generated by the boiler to generate electricity. ing. For example, Patent Document 3 discloses a waste incineration plant that recovers the combustion heat of waste with a waste heat boiler to generate electricity. In such an incineration plant, in order to suppress fluctuations in power generation, the amount of steam generated in the boiler (hereinafter referred to as "main steam amount") must be strictly maintained at the target steam amount corresponding to the target power generation amount. Is required.

Japanese Unexamined Patent Publication No. 2013-238350 Japanese Unexamined Patent Publication No. 2016-9809 Japanese Unexamined Patent Publication No. 2007-10258

The waste quality (ash content, calorific value, composition, etc.) of the waste put into the stoker type incinerator is usually not constant. When the amount of heat input to the incinerator decreases as the waste quality changes, it causes a shortage of the main steam amount. Therefore, in a conventional incinerator, automatic combustion control of an incinerator adjusts the amount of waste transported by the stoker and the amount of air for combustion based on the detected amount of main steam so that the amount of main steam becomes the target amount of steam. Is being done.

When maintaining the main steam amount at the target steam amount, especially when the main steam amount is insufficient, it is difficult to obtain a prompt response by the above-mentioned conventional automatic combustion control.

Therefore, the inventors of the present application provide a slow combustion region in a stoker-type incinerator in which the combustion of waste is suppressed as compared with the surroundings at a steady state, and perform combustion with a margin for rapidly increasing the amount of heat generated. I was inspired to do it.

The incinerator according to one aspect of the present invention includes an incinerator that incinerates waste, a boiler that generates steam by utilizing the heat of the exhaust gas of the incinerator, and a steam meter that detects the amount of steam generated by the boiler. And a combustion control device that controls the combustion of the incinerator based on the amount of steam detected by the steam meter. Then, the incinerator includes a multi-stage stoker including a combustion stoker, a combustion adjusting gas air box provided below the combustion stoker in a slow combustion region defined in at least a part of the combustion stoker, and the slow combustion stoker. The primary combustion air air box provided below the multi-stage stoker excluding the combustion area, the primary combustion air supply pipe that supplies the primary combustion air to the primary combustion air air box, and the combustion adjustment gas air box. A low oxygen gas supply pipe that supplies a low oxygen gas having a lower oxygen concentration than the primary combustion air and a high oxygen gas having an oxygen concentration equal to or higher than that of the primary combustion air are supplied to the combustion adjustment gas air box. It has a high oxygen gas supply pipe and a flow rate adjusting device for adjusting the flow rate of the low oxygen gas supplied to the combustion adjusting gas air box and the flow rate of the high oxygen gas supplied to the combustion adjusting gas air box. Then, the combustion control device controls the flow rate adjusting device so that only the low oxygen gas is supplied to the combustion adjusting gas air box when the detected steam amount is equal to or more than a predetermined target steam amount. Then, when the detected steam amount is less than the target steam amount, the low oxygen gas and the high oxygen gas, or only the high oxygen gas is supplied to the combustion adjusting gas air box. Control the flow regulator.

Similarly, the combustion control method for an incineration plant according to one aspect of the present invention is a waste incinerator having a plurality of stages of stokers including a combustion stoker and a boiler that generates steam by utilizing the heat of the exhaust gas of the incinerator. It is a combustion control method of an incineration plant provided with the above, in which the step of acquiring the amount of steam generated in the boiler and the amount of steam are adjusted to the lower part of the slow combustion region defined in at least a part of the combustion stoker. The combustion adjustment when the amount of combustion is equal to or more than a predetermined target amount of steam, including a step of supplying a combustion adjusting gas and supplying primary combustion air below the plurality of stages of the stoker excluding the slow combustion area. The gas for combustion is a low-oxygen gas having a lower oxygen concentration than the primary combustion air, and the combustion adjusting gas when the amount of steam is less than the target amount of steam has a higher oxygen concentration than the low-oxygen gas. It is characterized by being a gas.

In the incineration plant having the above configuration and its combustion control method, when the amount of steam generated in the boiler is equal to or greater than the target amount of steam, the combustion of waste (heat) in the slow combustion region of the combustion stoker is compared with the surroundings. (Including decomposition) is suppressed. In other words, the combustion of waste that has already started after entering the combustion stalker is temporarily calmed down in the slow combustion region. Although the combustion of waste in the slow combustion region is calmed down in this way, it rapidly increases as the amount of oxygen supplied increases. Therefore, when the heat input of the incinerator decreases, if a gas with a higher oxygen concentration than the low oxygen gas is supplied to the slow combustion area in response to the shortage of steam, the combustion of the waste in the slow combustion area will be quick. It can be promoted and the amount of steam can be increased rapidly. As a result, the amount of steam generated in the boiler can be stabilized.

In the incineration plant, the slow combustion region may be located on the downstream side of the upstream end in the waste flow direction of the combustion stalker and on the upstream side of the center of the waste flow direction of the combustion stalker. ..

As mentioned above, the combustion of waste is temporarily calmed down in the slow combustion region, but by arranging the slow combustion region in this way, the combustion of waste is promoted again on the combustion stalker on the downstream side of the slow combustion region. Sufficient combustion treatment is performed.

In the incinerator, the low oxygen gas supply pipe may be connected to the exhaust gas system of the incinerator, and the low oxygen gas may be the exhaust gas of the incinerator.

Similarly, in the combustion control method of the incinerator, the low oxygen gas may be the exhaust gas of the incinerator.

By using the exhaust gas having a lower oxygen concentration than the air generated in the system as the low oxygen gas, it is not necessary to separately generate the low oxygen gas, and the exhaust gas discharged to the outside can be reduced.

In the incineration plant, when the detected steam amount is less than the target steam amount, the combustion control device increases the difference based on the difference between the detected steam amount and the target steam amount. The flow rate adjusting device may be controlled so that the low oxygen gas and the high oxygen gas whose proportions are adjusted so as to increase the oxygen concentration according to the above are supplied.

Similarly, in the combustion control method of the incineration plant, when the steam amount is less than the target steam amount, the combustion adjusting gas has a large difference based on the difference between the steam amount and the target steam amount. It may be a gas prepared so that the oxygen concentration becomes higher as it becomes.

As a result, it is possible to prevent the amount of steam from becoming excessive when promoting the combustion of waste in the slow combustion region.

According to the present invention, it is generated from a boiler in an incinerator including a waste incinerator having a plurality of stages of stokers including a combustion stoker and a boiler that generates steam by utilizing the heat of the exhaust gas of the incinerator. When the amount of steam is insufficient with respect to the target amount of steam, the amount of steam can be increased promptly.

FIG. 1 is a diagram showing a schematic configuration of an incineration plant according to an embodiment of the present invention. FIG. 2 is a diagram showing a configuration of a control system of an incineration plant. FIG. 3 is a diagram showing a schematic configuration of the incinerator shown in FIG. FIG. 4 is a diagram showing a modified example of the combustion adjusting gas air box and the primary combustion air air box of the incinerator shown in FIG. FIG. 5 is a flowchart showing a flow of processing for combustion control of an incineration plant by a combustion control device. FIG. 6A is a diagram showing a state of combustion of garbage on the stalker when the main steam amount is equal to or more than the target steam amount, and FIG. 6B is a diagram showing the main steam amount less than the target steam amount. It is a figure which shows the state of the combustion of the garbage on the combustion stoker at that time. FIG. 7 is a diagram showing a modified example of an incinerator provided with a recirculating gas supply port on the furnace wall.

FIG. 1 shows a schematic configuration of an incineration plant 100 according to an embodiment of the present invention. The incinerator 100 recirculates the incinerator 1 that incinerates waste, the boiler 2 that recovers heat from the exhaust gas of the incinerator 1, the exhaust gas system 8 that treats the exhaust gas of the incinerator 1, and the exhaust gas to the incinerator 1. Includes an exhaust gas recirculation system 9. The incineration plant 100 further includes a pit 60 for temporarily storing waste as fuel, and a steam turbine generator 34 for generating electricity using the thermal energy recovered by the boiler 2. However, the pit 60 and the steam turbine generator 34 may be provided independently of the incineration plant 100.

[Incinerator 1]
The incinerator 1 is a parallel flow type stoker type incinerator. The incinerator 1 is provided with a main combustion chamber 14 and a recombustion chamber 19. The main combustion chamber 14 is provided with a drying stoker 15a, a combustion stoker 15b, and a post-combustion stoker 15c as means for transporting waste. The dry stoker 15a, the combustion stoker 15b, and the post-combustion stoker 15c are arranged in this order from the upstream to the downstream in the waste flow direction X.

The stokers 15a, 15b, and 15c are reciprocally driven by the stoker drive device 42 so as to send the dust to the downstream side in the dust flow direction X. The stoker drive device 42 includes drive cylinders 42a, 42b, 42c provided corresponding to the respective stokers 15a, 15b, 15c. By these drive cylinders 42a, 42b, 42c, the stokers 15a, 15b, 15c are oscillated and driven in conjunction with or independently.

At the lower part of each of the stokers 15a, 15b, 15c, a primary combustion air air box (hereinafter, simply referred to as "air box 16a, 16b, 16c") into which the primary combustion air is introduced is provided, and each air box 16a, A primary combustion air supply pipe 40 is connected to 16b and 16c. The primary combustion air sent from the primary combustion air supply pipe 40 to the air boxes 16a, 16b, 16c is supplied to the main combustion chamber 14 via the holes provided in the stokers 15a, 15b, 15c. The supply amount of the primary combustion air is adjusted by the flow rate adjusting device 43. The flow rate adjusting device 43 includes a push-in blower 43d that sends the primary combustion air to the air boxes 16a, 16b, 16c, and dampers 43a, 43b, 43c that adjust the supply amount of the primary combustion air to the air boxes 16a, 16b, 16c. And include. Further, a secondary combustion air supply pipe 45 is connected to the main combustion chamber 14. The secondary combustion air supply pipe 45 is provided with a push-in blower as a flow rate adjusting device 44, a damper (not shown), and the like. The secondary combustion air is supplied toward the inside of the main combustion chamber 14 and the inlet of the recombustion chamber 19. The supply amount of the secondary combustion air is adjusted by the flow rate adjusting device 44.

A charging hopper 12 is connected to the inlet of the main combustion chamber 14 via a chute 13. Further, at the inlet of the main combustion chamber 14, a feeder 41 for pushing out dust onto the drying stoker 15a is provided. The feeder 41 adjusts the amount of dust input to the main combustion chamber 14.

An inlet of the re-combustion chamber 19 is provided above the downstream portion of the post-combustion stoker 15c in the waste flow direction X. The recombustion chamber 19 extends obliquely upward from the downstream end of the main combustion chamber 14 in the flow direction of the combustion gas so as to vertically overlap the main combustion chamber 14. The combustion gas flowing in parallel with the garbage in the main combustion chamber 14 reverses the direction of flow at the inlet of the recombustion chamber 19, and further rises along the recombustion chamber 19 extending diagonally upward.

[Boiler 2]
The flues 20, 21 and 22, which are continuous with the reburning chamber 19 of the incinerator 1, are configured with a boiler 2 that recovers heat energy from the flue gas flowing through the flues 20, 21 and 22. Water pipes 23 connected to the boiler drum 24 are stretched around the walls of the first flue 20 and the second flue 21. Further, the boiler drum 24 is connected to the superheater tube 27 of the superheater 25. The superheater pipe 27 is installed in the third flue 22, and the steam passing through the superheater pipe 27 recovers the heat of the exhaust gas passing through the third flue 22. The amount of steam sent from the superheater 25 to the steam turbine generator 34 is an index of the amount of steam generated in the boiler 2, and is called the "main steam amount". The amount of main steam is measured by a steam meter 39 provided in a pipe connecting the superheater 25 and the steam turbine generator 34. The steam meter 39 is sufficient as long as it can directly or indirectly measure the amount of main steam. For example, the means for measuring the flow rate or pressure of steam before entering the superheater 25, the steam emitted from the superheater 25. It may be at least one of the means for measuring the flow rate or pressure.

An exhaust gas system 8 is connected to an exhaust port 29 provided in the third flue 22. The exhaust gas system 8 includes an exhaust passage 81 connected to the exhaust port 29, a bug filter 82 provided in the exhaust passage 81, an induction blower 83, and a chimney 84.

An exhaust gas recirculation system 9 is connected to the exhaust gas system 8. The exhaust gas recirculation system 9 takes out the exhaust gas from which soot and dust have been removed from the exhaust gas system 8 and recirculates it to the incinerator 1. The exhaust gas recirculation system 9 includes a recirculation path 91 connected to the downstream side of the bag filter 82 and the upstream side of the induction blower 83 in the exhaust path 81, and a push-in blower 92 provided in the recirculation path 91. The push-in blower 92 is a circulation amount adjusting means for changing the flow rate of the exhaust gas (hereinafter, referred to as “recirculation gas”) recirculated in the incinerator 1. Further, a damper (not shown) as a circulation amount adjusting means may be provided on the downstream side of the return passage 91 from the push blower 92. The return passage 91 may be configured so that a part of the exhaust gas discharged from the incinerator 1 is returned to the incinerator 1 as a recirculation gas, and is limited to the exhaust gas discharged from the third flue 22. Instead, the exhaust gas extracted from the other flues 20 and 21 and the recombustion chamber 19 may be returned to the incinerator 1.

In the incinerator 100 having the above configuration, waste is charged from the charging hopper 12 to the incinerator 1 through the chute 13. The dust put into the incinerator 1 is pushed out onto the drying stoker 15a by the feeder 41. While passing over the drying stoker 15a, the dust is dried and ignited by the primary combustion air and the radiant heat of the main combustion chamber 14. A part of the ignited garbage is thermally decomposed while passing over the combustion stoker 15b, and flammable pyrolysis gas is generated. This pyrolysis gas rides on the primary combustion air and moves to the upper part of the main combustion chamber 14, and is flame-combusted together with the secondary combustion air. The heat radiation associated with this flame combustion further raises the temperature of the waste. Further, the remaining portion of the ignited garbage is burned while passing over the combustion stoker 15b and the post-combustion stoker 15c, and the incineration ash remaining after combustion is discharged from the discharge chute 18 and treated by an ash treatment facility (not shown). The combustion exhaust gas of the main combustion chamber 14 is mixed with the secondary combustion air blown out to the inlet of the recombustion chamber 19, and is completely burned in the recombustion chamber 19.

In the boiler 2, the heat recovery water flowing through the water pipe 23 recovers the heat of the first flue 20 and the second flue 21 and returns to the boiler drum 24 in a saturated steam state. The steam of the boiler drum 24 is sent to the superheater 25. In the superheater 25, the steam sent from the boiler drum 24 is heated to a higher temperature while passing through the superheater tube 27, and is sent to the steam turbine generator 34.

Further, the exhaust gas that has passed through the flues 20, 21 and 22 is discharged to the exhaust gas system 8. In the exhaust gas system 8, the exhaust gas is discharged from the chimney 84 to the atmosphere after the soot and dust are separated by the bag filter 82. In the exhaust gas recirculation system 9, the exhaust gas from which soot and dust have been removed by the bag filter 82 is returned to the incinerator 1 through the recirculation path 91.

The operation of the incineration plant 100 having the above configuration is controlled by the combustion control device 10. FIG. 2 is a diagram showing a configuration of a control system of the incineration plant 100. As shown in FIG. 2, the combustion control device 10 includes devices such as a feeder 41, a stoker drive device 42, a flow rate adjusting device 43, 44, a low oxygen gas flow rate adjusting device 75 and a high oxygen gas flow rate adjusting device 76, which will be described later. It is connected to the device wirelessly or by wire, and can send and receive information and signals to and from those devices. Further, the combustion control device 10 is wirelessly or wiredly connected to various instruments such as the vapor meter 39, and can receive detection signals from those instruments.

The combustion control device 10 is a so-called computer, and has an arithmetic processing unit such as a CPU and a storage unit such as a ROM and a RAM (none of which are shown). The storage unit stores programs executed by the arithmetic processing unit, various fixed data, and the like. The arithmetic processing unit transmits / receives data to / from an external device. In addition, the arithmetic processing unit inputs detection signals from various sensors and outputs control signals to each control target. In the combustion control device 10, the arithmetic processing unit reads out and executes software such as a program stored in the storage unit, so that processing for controlling the operation of each component of the incineration plant 100 is performed. The combustion control device 10 may execute each process by centralized control by a single computer, or may execute each process by distributed control by cooperation of a plurality of computers. Further, the combustion control device 10 may be composed of a microprocessor, a programmable logic controller (PLC) and the like.

[Combustion control method for incineration plant 100]
Subsequently, the combustion control method of the incinerator 1 in the incinerator 100 will be described. The combustion control device 10 controls the combustion of the incinerator 1 so as to keep the main steam amount at a predetermined target steam amount in order to stabilize the power generation amount of the steam turbine generator 34.

As shown in FIG. 3, a slow combustion region 7 is defined in at least a part of the combustion stoker 15b. In the present embodiment, the slow combustion region 7 is defined at one location of the combustion stoker 15b, but the slow combustion region 7 may be defined at a plurality of locations of the combustion stoker 15b. The slow combustion region 7 is preferably located on the downstream side of the upstream end portion of the waste flow direction X of the combustion stoker 15b and on the upstream side of the center of the waste flow direction X of the combustion stoker 15b.

The dimensions of the slow combustion region 7 and the combustion stoker 15b in the furnace width direction (the depth direction of the paper in FIG. 3) are substantially the same, and the slow combustion region 7 is provided over the entire furnace width direction of the combustion stoker 15b. There is. The size of the waste flow direction X in the slow combustion region 7 is about 20 to 50% of the size of the waste flow direction X of the combustion stoker 15b. If it is less than 20%, it is difficult to obtain a sufficient effect of adjusting combustion. On the other hand, if it exceeds 50%, the combustion treatment of waste may be insufficient.

In the slow combustion region 7, below the combustion stoker 15b, a combustion adjustment gas air box 71 into which the combustion adjustment gas is introduced is provided. The dimensions of the combustion adjusting gas air box 71 in the furnace width direction are substantially the same as the dimensions of the combustion stoker 15b in the furnace width direction. The size of the waste flow direction X of the combustion adjusting gas air box 71 is about 20 to 50% of the size of the waste flow direction X of the combustion stoker 15b. In FIG. 3, the combustion adjusting gas air box 71 is arranged inside the air box 16b of the combustion stoker 15b, but as shown in FIG. 4, the air box 16b of the combustion stoker 15b is divided in the dust flow direction X, and they are divided. A combustion adjusting gas air box 71 may be provided between the two. The internal space of the air box 16b and the internal space of the combustion adjusting gas air box 71 are separated from each other so that the primary combustion air in the air box 16b does not enter the combustion adjusting gas air box 71.

The combustion adjustment gas air box 71 includes a low oxygen gas supply pipe 72 that supplies low oxygen gas to the combustion adjustment gas air box 71, and a high oxygen gas supply pipe 73 that supplies high oxygen gas to the combustion adjustment gas air box 71. Is connected. Here, the "low oxygen gas" is a gas having an oxygen concentration lower than that of the primary combustion air. For example, when the oxygen concentration of the primary combustion air is about 21% by volume, which is the same as that of air, the oxygen concentration of the low oxygen gas may be 15% by volume or less. Further, the "high oxygen gas" is a gas having the same or higher oxygen concentration as the primary combustion air. For example, when the oxygen concentration of the primary combustion air is about 21% by volume, the oxygen concentration of the high oxygen gas may be 21 to 30% by volume. The high oxygen gas may be, for example, air or oxygen-enriched air.

The low oxygen gas supply pipe 72 is provided with a low oxygen gas flow rate adjusting device 75 that adjusts the flow rate of the low oxygen gas supplied from the low oxygen gas source to the combustion adjusting gas air box 71. Further, the high oxygen gas supply pipe 73 is provided with a high oxygen gas flow rate adjusting device 76 for adjusting the flow rate of the high oxygen gas supplied from the high oxygen gas source to the combustion adjusting gas air box 71. The low oxygen gas flow rate adjusting device 75 and the high oxygen gas flow rate adjusting device 76 are controlled by the combustion control device 10. Each of the low oxygen gas flow rate adjusting device 75 and the high oxygen gas flow rate adjusting device 76 is composed of one or a combination of two or more of known gas flow rate adjusting means such as a damper, a flow rate adjusting valve, and a blower. It's okay. By the operation of the low oxygen gas flow rate adjusting device 75 and the high oxygen gas flow rate adjusting device 76, only the low oxygen gas is supplied to the combustion adjusting gas air box 71, and only the high oxygen gas is supplied to the combustion adjusting gas air box 71. , The state in which the low oxygen gas and the high oxygen gas whose proportions are adjusted are supplied to the combustion adjustment gas air box 71, and the state in which neither the low oxygen gas nor the high oxygen gas is supplied to the combustion adjustment gas air box 71. You can switch the state.

In this embodiment, the exhaust gas recirculation system 9 is used as a low oxygen gas source for the low oxygen gas supply pipe 72. Specifically, the low oxygen gas supply pipe 72 is connected to the return passage 91 of the exhaust gas return system 9, and the recirculated gas as low oxygen gas is sent to the combustion adjustment gas air box 71 through the low oxygen gas supply pipe 72. Be done. The low oxygen gas flow rate adjusting device 75 in this case may be a push blower 92 provided in the recirculation gas return path 91. However, as the low oxygen gas flow rate adjusting device 75, a flow rate adjusting means such as a damper or a blower may be used in place of or in addition to the push-in blower 92.

FIG. 5 is a flowchart showing a flow of combustion control processing of the incineration plant 100 by the combustion control device 10. In this flowchart, the operation of the incinerator 1 is stable, and the main steam amount starts from a state in which the main steam amount is equal to or more than a predetermined target steam amount.

When the main steam amount is equal to or more than the target steam amount, that is, when the main steam amount is sufficient, the combustion control device 10 supplies the low oxygen gas as the combustion adjusting gas to the combustion adjusting gas air box 71. It controls the low oxygen gas flow rate adjusting device 75 and the high oxygen gas flow rate adjusting device 76.

In this way, when there is no shortage of the main steam amount, low oxygen gas having a lower oxygen concentration than the primary combustion air is supplied below the combustion stoker 15b in the slow combustion region 7, and the combustion stoker 15b excluding the slow combustion region 7 is supplied. Primary combustion air is supplied below. That is, the oxygen concentration distribution acting on the dust on the combustion stoker 15b is biased, and the oxygen concentration in the slow combustion region 7 is lower than that in the surroundings. As a result, as shown in FIG. 6A, the combustion of waste (including thermal decomposition) is suppressed in the slow combustion region 7 as compared with the surroundings. Note that FIG. 6A shows the state of combustion of garbage on the stoker when the main steam amount is equal to or more than the target steam amount, and F in the figure represents a flame.

As shown in FIG. 5, the combustion control device 10 monitors the amount of main steam detected by the steam meter 39 during operation. Specifically, the combustion control device 10 acquires the detected main steam amount (step S1), compares it with the target steam amount, and determines whether or not the main steam amount is equal to or greater than the target steam amount. (Step S2).

In the combustion control device 10, when the main steam amount is lower than the target steam amount (NO in step S2), that is, when the main steam amount is insufficient, the combustion adjusting gas having a higher oxygen concentration than the low oxygen gas is used as the combustion adjusting gas wind. The low oxygen gas flow rate adjusting device 75 and the high oxygen gas flow rate adjusting device 76 are operated so as to be supplied to the box 71 (step S3). Here, the combustion adjusting gas may be composed only of the high oxygen gas supplied from the high oxygen gas supply pipe 73. Alternatively, based on the difference between the main steam amount detected by the steam meter 39 and the target steam amount, that is, the shortage amount of the main steam amount, the oxygen concentration of the combustion adjusting gas increases as the shortage amount of the main steam amount increases. The ratio of low oxygen gas to high oxygen gas may be adjusted so as to be high. Further, the oxygen concentration of the combustion adjusting gas may be the same as that of the primary combustion air.

As described above, when the main steam amount is insufficient, the combustion adjusting gas having a higher oxygen concentration than the low oxygen gas is supplied from below the combustion stoker 15b in the slow combustion region 7. As a result, as shown in FIG. 6B, the combustion of waste in the slow combustion region 7 is promoted, and the amount of main steam increases. Note that FIG. 6B shows the state of combustion of garbage on the stoker when the main steam amount is less than the target steam amount, and F in the figure represents a flame.

The combustion control device 10 still acquires the main steam amount and continues to monitor the value (step S4), and if the detected main steam amount exceeds the target steam amount (YES in step S5), the combustion adjusting gas The low oxygen gas flow rate adjusting device 75 and the high oxygen gas flow rate adjusting device 76 are controlled so that the low oxygen gas is supplied to the combustion adjusting gas air box 71 (step S6).

Regardless of the excess or deficiency of the main steam amount, the flow rate of the combustion adjustment gas supplied to the combustion adjustment gas air box 71 differs between the combustion adjustment gas of the combustion adjustment gas air box 71 and the primary combustion air of the air box 16b. The value is set so that no pressure is generated and the total amount of the combustion adjusting gas supplied to the combustion adjusting gas air box 71 and the primary combustion air supplied to the air box 16b is maintained at a predetermined target flow rate. The target flow rate may be determined from the relationship between the detected main steam amount and the target main steam amount.

As described above, the incinerator 100 according to the present embodiment is generated by the incinerator 1 that incinerates waste, the boiler 2 that generates steam by utilizing the heat of the exhaust gas of the incinerator 1, and the boiler 2. A steam meter 39 that detects the amount of steam, and a combustion control device 10 that controls combustion of the incinerator 1 based on the amount of steam detected by the steam meter 39 (more specifically, the amount of steam and various process values). It has. Then, the incinerator 1 is provided with a plurality of stages of the stalker 15a, 15b, 15c including the combustion stalker 15b and a combustion adjusting gas provided below the combustion stalker in the slow combustion region 7 defined in at least a part of the combustion stalker 15b. The air box 71, the primary combustion air air boxes 16a, 16b, 16c provided below the multi-stage stokers 15a, 15b, 15c excluding the slow combustion area 7, and the primary combustion air air boxes 16a, 16b, 16c. The primary combustion air supply pipe 40 that supplies the primary combustion air, the low oxygen gas supply pipe 72 that supplies the low oxygen gas having a lower oxygen concentration than the primary combustion air to the combustion adjustment gas air box 71, and the combustion adjustment gas air box 71. High oxygen gas supply pipe 73 that supplies high oxygen gas having an oxygen concentration equal to or higher than that of the primary combustion air, and the flow rate of low oxygen gas supplied to the combustion adjustment gas air box 71 and the combustion adjustment gas air box 71. It has flow control devices 75 and 76 that adjust the flow rate of the high oxygen gas supplied to. Then, when the detected steam amount is equal to or higher than the predetermined target steam amount, the combustion control device 10 controls and detects the flow rate adjusting device so that only the low oxygen gas is supplied to the combustion adjusting gas air box 71. When the steam amount is less than the target steam amount, the flow rate adjusting devices 75 and 76 are controlled so that only low oxygen gas, high oxygen gas, or high oxygen gas is supplied to the combustion adjusting gas air box 71. ..

Similarly, the combustion control method of the incineration plant 100 according to the present embodiment utilizes the heat of the waste incinerator 1 having a plurality of stages of stokers 15a, 15b, 15c including the combustion stoker 15b and the exhaust gas of the incinerator 1. A combustion control method for an incineration plant 100 including a boiler 2 that generates steam, a step of acquiring the amount of steam generated in the boiler 2 and a slow combustion region 7 defined in at least a part of the combustion stoker 15b. A step of supplying combustion adjusting gas according to the amount of combustion to the lower part of the above and supplying primary combustion air to the lower part of the plurality of stages of the stokers 15a, 15b, 15c excluding the slow combustion area 7, and the amount of the steam is predetermined. The combustion adjustment gas when the amount of combustion is equal to or more than the target amount is a low oxygen gas having a lower oxygen concentration than the primary combustion air, and the combustion adjustment gas when the amount of steam is less than the target amount of steam is more than the low oxygen gas. Is also characterized by being a gas with a high oxygen concentration.

In the incineration plant 100 having the above configuration and its combustion control method, when the amount of steam generated in the boiler 2 is equal to or greater than the target amount of steam, the slow combustion area 7 of the combustion stoker 15b is compared with the surroundings. Combustion (including thermal decomposition) is suppressed. That is, the combustion of the waste that has already started after entering the combustion stoker 15b is temporarily calmed down in the slow combustion region 7. Although the combustion of waste in the slow combustion region 7 is calmed down in this way, it rapidly increases as the amount of oxygen supplied increases. Therefore, when the heat input of the incinerator 1 decreases, if a gas having a higher oxygen concentration than the low oxygen gas is supplied to the slow combustion region 7 in response to the insufficient amount of steam, the waste in the slow combustion region 7 is burned. Can be rapidly increased and the amount of steam can be increased quickly. As a result, the amount of steam generated in the boiler 2 can be stabilized.

Further, in the incineration plant 100 according to the present embodiment, the slow combustion region 7 is on the downstream side of the upstream end of the waste flow direction X of the combustion stoker 15b, and is at the center of the waste flow direction X of the combustion stoker 15b. It is located upstream of.

As described above, the combustion of waste is temporarily calmed down in the slow combustion region 7, but by arranging the slow combustion region 7 in this way, the waste is again put on the combustion stoker 15b on the downstream side of the slow combustion region 7. Combustion is promoted and sufficient combustion treatment is performed. However, although it is desirable that the slow combustion region 7 is arranged as described above, the slow combustion region 7 is not limited to the above arrangement as long as it is on the combustion stoker 15b. Further, the slow combustion region 7 may be defined as a region downstream of the dust flow direction X of the dry stoker 15a where the dust is ignited and burned.

Further, in the incinerator 100 according to the present embodiment, the low oxygen gas supply pipe 72 is connected to the exhaust gas system 8 (more specifically, the exhaust gas recirculation system 9) of the incinerator 1, and the low oxygen gas is incinerated. It is the exhaust gas of 1. Similarly, in the combustion control method of the incinerator 100 according to the present embodiment, the low oxygen gas is the exhaust gas of the incinerator.

By using the exhaust gas having a lower oxygen concentration than the air generated in the system as the low oxygen gas, it is not necessary to separately generate the low oxygen gas, and the exhaust gas discharged to the outside can be reduced. However, the low oxygen gas is not limited to the recirculated gas, and a gas having an oxygen concentration lower than that of the prepared primary combustion air may be used as the low oxygen gas.

Further, in the incineration plant 100 according to the present embodiment, when the detected steam amount is less than the target steam amount, the combustion control device 10 makes a difference based on the difference between the detected steam amount and the target steam amount. The flow rate adjusting devices 75 and 76 are configured to control the flow rate adjusting devices 75 and 76 so that the low oxygen gas and the high oxygen gas whose proportions are adjusted so that the oxygen concentration increases as the amount increases. Similarly, in the combustion control method of the incineration plant 100 according to the present embodiment, the difference in the combustion adjusting gas when the steam amount is less than the target steam amount becomes large based on the difference between the steam amount and the target steam amount. It is a gas prepared so that the oxygen concentration increases accordingly.

As a result, it is possible to prevent the amount of steam from becoming excessive when promoting the combustion of the waste in the slow combustion region 7. However, when the detected steam amount is less than the target steam amount, the oxygen concentration of the combustion adjustment gas supplied to the combustion adjustment gas air box 71 is a predetermined value regardless of the difference between the steam amount and the target steam amount. It may be.

Although the preferred embodiment of the present invention has been described above, the present invention may include modified details of the specific structure and / or function of the above embodiment without departing from the spirit of the present invention. .. The above configuration can be changed, for example, as follows.

For example, in the incinerator 1 of the incinerator 100 according to the above embodiment, an air diffuser pipe for ejecting the combustion adjusting gas may be provided instead of the combustion adjusting gas air box 71.

Further, for example, in the incineration plant 100 according to the above embodiment, the equipment that uses the steam of the boiler 2 is the steam turbine generator 34, but instead of or in addition to the steam turbine generator 34, steam utilization different from that of the generator is used. Equipment may be provided.

Further, for example, in the incinerator 1 of the incinerator 100 according to the above embodiment, as shown in FIG. 7, a plurality of recirculation gas supply ports for supplying the recirculation gas to the main combustion chamber 14 on the furnace wall of the incinerator 1. 95 may be provided. A recirculation gas supply pipe 97 connected to the recirculation passage 91 is connected to each recirculation gas supply port 95, and the recirculation gas supply pipe 97 is supplied with the recirculation gas from each recirculation gas supply port 95. A flow rate adjusting device 96 for adjusting the amount (or switching the presence or absence of supply) is provided. The flow rate adjusting device 96 may be at least one of known flow rate adjusting means such as a flow rate adjusting valve, a damper, and a blower.

When the recirculation gas supply port 95 is provided in the incinerator 1 as described above, the combustion control device 10 uses the combustion control device 10 when the main steam amount is equal to or more than the target main steam amount, that is, the slow combustion region 7 is used to slow down the waste. When combustion is being performed, the supply of the recirculated gas from the recirculated gas supply port 95 that supplies the recirculated gas to the slow combustion region 7 among the plurality of recirculated gas supply ports 95 is stopped, and the remainder is left. Each flow rate adjusting device 96 is controlled so as to allow the supply of the recirculated gas from the recirculated gas supply port 95 of the above. Further, when the main steam flow rate is less than the target steam amount, that is, when the combustion of waste is promoted in the slow combustion region 7, the combustion control device 10 re-supplies the recirculated gas to the slow combustion region 7. Each flow rate adjusting device 96 is controlled so as to allow the supply of the recirculated gas from the recirculated gas supply port 95 including the circulating gas supply port 95. In this way, the recirculated gas supplied from the recirculated gas supply port 95 is used for combustion of the pyrolysis gas as a part of the secondary combustion air. Therefore, when the main steam amount is insufficient with respect to the target main steam amount, the recirculation gas is supplied from the slow combustion area 7 and the corresponding recirculation gas supply port 95, so that the waste in the slow combustion area 7 is burned. Can be further promoted.

100: Incineration plant 1: Incinerator 2: Boiler 7: Slow combustion area 8: Exhaust gas system 9: Exhaust gas recirculation system 10: Combustion control device 12: Input hopper 13: Chute 14: Main combustion chambers 15a, 15b, 15c: Stoker 16a , 16b, 16c: Primary combustion air air box 18: Exhaust chute 19: Recombustion chamber 20, 21 and 22: Chimney 23: Water pipe 24: Boiler drum 25: Superheater 27: Overheating pipe 29: Exhaust port 81: Exhaust path 82: Bug filter 83: Attracting blower 84: Chimney 34: Steam turbine generator 39: Steam meter 40: Primary combustion air supply pipe 41: Feeder 42: Stoker drive device 42a, 42b, 42c: Drive cylinder 43, 44: Flow rate Adjustment device 43a, 43b, 43c: Damper 43d: Push-in blower 45: Secondary combustion air supply pipe 60: Pit 71: Combustion adjustment gas air box 72: Low oxygen gas supply pipe 73: High oxygen gas supply pipe 75: Low oxygen gas Flow rate adjusting device 76: High oxygen gas flow rate adjusting device 91: Circulation path 92: Push-in blower 95: Recirculating gas supply port 96: Flow rate adjusting device 97: Recirculating gas supply pipe

Claims (7)

An incinerator that incinerates waste, a boiler that uses the heat of the exhaust gas from the incinerator to generate steam, a steam meter that detects the amount of steam generated by the boiler, and steam detected by the steam meter. It is equipped with a combustion control device that controls the combustion of the incinerator based on the amount.
The incinerator
With multiple stages of stalking, including burning stalking,
A combustion control gas air box provided below the combustion stoker in a slow combustion region defined in at least a part of the combustion stoker.
A primary combustion air air box provided below the multi-stage stoker excluding the slow combustion region, and
The primary combustion air supply pipe that supplies the primary combustion air to the primary combustion air air box,
A low oxygen gas supply pipe that supplies a low oxygen gas having a lower oxygen concentration than the primary combustion air to the combustion adjustment gas air box, and
A high oxygen gas supply pipe that supplies high oxygen gas having an oxygen concentration equal to or higher than that of the primary combustion air to the combustion adjustment gas air box.
It has a flow rate adjusting device for adjusting the flow rate of the low oxygen gas supplied to the combustion adjusting gas air box and the flow rate of the high oxygen gas supplied to the combustion adjusting gas air box.
When the detected amount of steam is equal to or greater than a predetermined target amount of steam, the combustion control device controls the flow rate adjusting device so that only the low oxygen gas is supplied to the combustion adjusting gas air box. When the detected amount of steam is less than the target amount of steam, the flow rate is adjusted so that only the low oxygen gas and the high oxygen gas or the high oxygen gas are supplied to the combustion adjusting gas air box. Control the device,
Incineration plant. The slow combustion region is located on the downstream side of the upstream end in the waste flow direction of the combustion stalker and on the upstream side of the center of the waste flow direction of the combustion stalker.
The incineration plant according to claim 1. The low oxygen gas supply pipe is connected to the exhaust gas system of the incinerator, and the low oxygen gas is the exhaust gas of the incinerator.
The incineration plant according to claim 1 or 2. When the detected steam amount is less than the target steam amount, the combustion control device increases the oxygen concentration as the difference increases, based on the difference between the detected steam amount and the target steam amount. The flow rate adjusting device is controlled so that the low oxygen gas and the high oxygen gas whose proportions are adjusted so as to be supplied are supplied.
The incineration plant according to any one of claims 1 to 3. A combustion control method for an incinerator equipped with a waste incinerator having a plurality of stages of incinerators including a combustion stoker and a boiler that generates steam by utilizing the heat of the exhaust gas of the incinerator.
The step of acquiring the amount of steam generated in the boiler and
A combustion adjusting gas according to the amount of steam is supplied below the slow combustion region defined in at least a part of the combustion stoker, and primary combustion air is supplied below the plurality of stages of the stoker excluding the slow combustion region. Including steps to do
When the amount of steam is equal to or greater than a predetermined target amount of steam, the combustion adjusting gas is a low-oxygen gas having an oxygen concentration lower than that of the primary combustion air.
When the vapor amount is less than the target vapor amount, the combustion adjusting gas is a gas having a higher oxygen concentration than the low oxygen gas.
Combustion control method for incineration plants. The low oxygen gas is the exhaust gas of the incinerator.
The combustion control method for an incineration plant according to claim 5. When the amount of steam is less than the target amount of steam, the proportion of the combustion adjusting gas is adjusted based on the difference between the amount of steam and the target amount of steam so that the oxygen concentration increases as the difference increases. Is the gas
The combustion control method for an incineration plant according to claim 5 or 6.

Images