JP2002267101A - Method for superheating steam in incinerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve power generating efficiency and thermal energy efficiency without any problem on high temperature corrosion in a superheater. SOLUTION: Combustion gas is drawn out from an after-combustion part to effect after-combustion of a substance to be burnt being main-burnt in a primary combustion chamber 7a to effect main combustion of the substance to be burnt by primary combustion air. After the combustion gas is introduced in a dust collecting device 17, it is introduced in a secondary superheater 22, and steam is superheated by the secondary superheater 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for superheating steam in an incinerator for incinerating materials such as wastes.

[0002]

2. Description of the Related Art Generally, most waste such as municipal waste is incinerated by a waste incineration plant including an incinerator. Here, in the type often used as an incinerator,
There is a stoker type incinerator.

FIG. 5 shows a schematic configuration of a conventional stoker type incinerator. In the incinerator 100, a hopper 102 into which refuse 101 as a combustible
And a stoker 104 for burning the refuse 101 pushed out from the lower part of the hopper 102 by the pusher 103.
And a combustion chamber 106 defined by a furnace wall 105 above the stoker 104, and below the combustion chamber 106 through the stoker 104.
Primary combustion air supply device 10 for supplying primary combustion air to the inside
7 is provided, and an ash outlet 108 for taking out incinerated ash after combustion is provided downstream of the stoker 104.

The stoker 104 generally includes a drying stoker 104a, a combustion stoker 104b, and a post-combustion stoker 104c in this order from the upstream side. Below the stokers 104a, 104b, and 104c, the stoker 104 corresponds to each stoker. Each air conduit 107a, 107b, 107c of the primary combustion air supply device 107 is provided, respectively. Note that these air conduits 107a, 107b, 10
7c is supplied with the primary combustion air from the blower 107d. The combustion chamber 106 includes a primary combustion chamber 106a for burning the dust 101 on the stoker 104 with the primary combustion air, and C generated in the primary combustion chamber 106a.
The secondary combustion chamber 106b is configured to burn unburned gas such as O or unburned matter with the secondary combustion air supplied from the secondary combustion air supply pipe 109 above the unburned gas.

In such a configuration, the refuse 101 introduced from the hopper 102 is sequentially supplied to the drying stoker 104a by the pusher 103, and the primary combustion air supplied from below and the high temperature state are supplied to the drying stoker 104a. Is heated and dried by radiant heat from the primary combustion chamber 106a. As a result, moisture and volatile components in the refuse 101 evaporate, and unburned gases such as CO and HC are released.

[0006] Thereafter, the refuse 101 dried by passing through the drying stoker 104a is burned on the combustion stoker 104b by primary combustion air supplied from an air conduit 107b, and a burn-off point is provided downstream of the combustion stoker 104b. Reach Next, the refuse 101 is sent to a post-combustion stoker 104c, in which so-called burning is performed by primary combustion air supplied from an air conduit 107c on the post-combustion stoker 104c, and incinerated ash is taken out from an ash discharge port 108. On the other hand, unburned gas and unburned matter generated by incineration of the refuse 101 are completely burned by primary combustion air supplied from below the stoker 104 and secondary combustion air supplied to the secondary combustion chamber 106b, and then exhausted. It is discharged from the outlet 110.

In the above-described incinerator, high-temperature exhaust gas is discharged from the exhaust gas outlet 110 into the exhaust gas passage along with the incineration of the waste. Therefore, a waste heat boiler is installed in the exhaust gas passage. The heat energy contained in the high-temperature exhaust gas is extracted in the form of steam by an exhaust heat boiler, and the steam turbine is driven to be used for power generation.

A conventional typical power generation system utilizing this waste heat will be described with reference to FIG. In this power generation system, the exhaust gas from the incinerator 100
Through the chimney 121. In the exhaust gas duct 120, an exhaust heat boiler 122 for recovering heat from high-temperature exhaust gas is arranged, and HCl, SO _X ,
A dry gas treatment device 123 and a wet gas treatment device 124 as exhaust gas treatment equipment for removing air pollutants such as soot and dust, and an induction blower 125 are arranged. A denitration device 126 is provided downstream of the wet gas treatment device 124, and a gas reheater 127 for reheating gas is provided upstream of the denitration device 126. On the other hand, the steam from the exhaust heat boiler 122
8, the steam turbine 129 is driven, and the rotation of the steam turbine 129 drives the generator 130. further,
The condensate from the steam turbine 129 passes through a condenser 132 and a deaerator 133 by a condenser pipe 131, and is discharged from the heat-recovery boiler 122.
It is circulated and used for water supply.

[0009]

However, in the above-described waste power generation, high temperature joint corrosion occurs in a superheater and the like due to hydrogen chloride (HCl) and various corrosive substances contained in exhaust gas. In order to prevent this, it is customary to keep the steam temperature within a temperature range in which corrosion does not easily occur (practically 300 ° C. or less), and thus the power generation efficiency must be reduced. is there.

[0010] Therefore, in order to improve the power generation efficiency in this refuse power generation, an independent steam superheater is provided which superheats the steam from the exhaust heat boiler by burning the hydrocarbon fuel,
A system has been proposed in which the steam is superheated by the steam superheater and then sent to a steam turbine. In such a system, it is necessary to supply a considerable amount of fuel to the steam superheater, and the CO ₂ emission amount is reduced. Leads to an increase in

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and there is provided a method for superheating steam in an incinerator, which does not have the problem of high-temperature corrosion in a superheater and can improve power generation efficiency and thermal energy efficiency. It is intended to provide.

[0012]

In order to achieve the above object, a method for superheating steam in an incinerator according to a first aspect of the present invention comprises a primary combustion chamber in which an object to be burned is primarily burned by primary combustion air; A secondary combustion chamber for completely combusting unburned matter generated in the primary combustion chamber with secondary combustion air, and after post-combustion of the main combustible in the primary combustion chamber in the primary combustion chamber. In the incinerator having a combustion section, while introducing the combustion gas extracted from the post-combustion section to the dust collector, and introducing the combustion gas after dust has been removed by the dust collector to the superheater, The superheater performs steam superheating.

According to the present invention, the combustion gas extracted from the post-combustion portion of the primary combustion chamber is introduced into the superheater after being removed by the dust collector, and the superheater performs steam superheating. Therefore, since the combustion gas supplied to the superheater contains no dust and has a low concentration of hydrogen chloride (HCl), there is no problem of pipe corrosion in the superheater, and the steam temperature after passing through the superheater is reduced. Can be raised to about 500 ° C. to improve the power generation efficiency, and the thermal energy efficiency can be improved without extra energy consumption.
Further, since there is no problem of dust, the piping pitch in the superheater can be reduced, and the superheater can be downsized. Further, compared to the case where the dust collecting device is provided on the exhaust gas outlet side of the incinerator, the dust collecting device can be downsized and there is an advantage in space. Furthermore, there is the combustion gas in the combustion unit after in oxygen-rich state is withdrawn, it can be the primary combustion chamber to a strong reducing atmosphere, the effect of generation of the NO _X can be suppressed. In addition, if the power generation efficiency can be improved as described above, the power generation amount of the existing furnace can be increased, so that fossil fuel can be reduced and, as a result, CO ₂ reduction measures can be taken.

Next, a method for superheating steam in an incinerator according to a second invention is a method of superheating a combustion target with primary combustion air in a primary combustion chamber, and converting unburnt substances generated in the primary combustion chamber into secondary combustion air. In the incinerator comprising a secondary combustion chamber for complete combustion by introducing a combustion gas drawn out from the vicinity of an exhaust gas outlet above the secondary combustion chamber into a dust collector, and after the dust is removed by the dust collector, Is introduced into the superheater, and the superheater performs steam superheating.

According to the present invention, the outlet of the combustion gas from the incinerator is located near the exhaust gas outlet above the secondary combustion chamber instead of the post-combustion section as in the first invention. With such a configuration, the same operation and effect as the first invention can be obtained. Further, when the combustion gas (exhaust gas) near the exhaust gas outlet is extracted as in the present invention, the temperature of the extracted gas can be increased and the amount of the extracted gas can be freely set. .

In each of the above inventions, a primary superheater is provided in the exhaust gas passage of the incinerator, and the steam heated to a predetermined temperature by the primary superheater is guided to the superheater downstream of the dust collector. It is preferable to carry out the method (third invention). By doing so, the steam temperature in the primary superheater can be suppressed to a temperature range in which corrosion does not easily occur (about 300 to 400 ° C.), and the steam temperature can be further increased in the secondary superheater. It can be further improved.

In the first to third aspects of the present invention, it is preferable that the combustion gas after passing through the superheater is supplied to an upstream side of a supply position of the secondary combustion air to agitate and mix the combustion chamber. 4th invention). By doing so, the combustion chamber upstream of the secondary combustion air supply position can be made a weak reducing atmosphere in which the composition distribution and temperature of the combustion gas are uniform, and the unburned gas and unburned substances are completely burned. it is possible to, the generation of CO and NO _X can be significantly suppressed. As a result, the amount of supply air originally used for agitation and mixing can be reduced, and thus the amount of exhaust gas discharged from the incinerator can be reduced, thereby disposing the air downstream of the incinerator. It is possible to reduce the size of the exhaust gas treatment equipment and the like.

Further, the combustion gas after passing through the superheater may be mixed with the primary combustion air and supplied to an upstream side of a post-combustion section in the primary combustion chamber (a fifth invention). In this way, the amount of combustion air that should be supplied to the primary combustion chamber can be reduced, and the amount of exhaust gas discharged from the incinerator can be reduced. Processing equipment and the like can be reduced in size.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a specific embodiment of the steam superheating method in an incinerator according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an incinerator according to one embodiment of the present invention.

In the incinerator 1 of the present embodiment, a hopper 3 into which refuse 2 as a substance to be burned is put, and refuse 2 pushed out from a lower portion of the hopper 3 by a pusher 4.
And a combustion chamber 7 defined by a furnace wall 6 above the stoker 5. Below the combustion chamber 7, primary combustion air is introduced into the combustion chamber 7 through the stoker 5. Is provided, and an ash outlet 9 for taking out incinerated ash after combustion is provided downstream of the stoker 5.

The stoker 5 is composed of a drying stoker 5a, a burning stoker 5b and a post-burning stoker 5c in this order from the upstream side, and each of the stoker 5a, 5b, 5c.
The air conduits 8a, 8b, 8c of the primary combustion air supply device 8 are respectively provided below the stoker corresponding to the stoker. Primary combustion air is supplied to these air conduits 8a, 8b, 8c from a forced blower 8d. The air conduits 8a, 8b, 8c are provided with adjusting dampers 10a, 10b, 10c for adjusting the supply amount of the primary combustion air, respectively. These adjusting dampers 10a, 10b, 10c are opened by a damper driving device (not shown). The degree is adjusted.

The combustion chamber 7 includes a primary combustion chamber 7a for burning the refuse 2 on the stoker 5 with the primary combustion air, and an unburned gas or unburned substance such as CO generated in the primary combustion chamber 7a. And a secondary combustion chamber 7b that burns with the secondary combustion air supplied from the secondary combustion air supply pipe 11 above. The upper part of the secondary combustion chamber 7b is communicated with the exhaust gas passage 12 via an exhaust gas outlet.

The exhaust gas passage 12 is provided with a boiler 13 for generating steam by heat exchange with the exhaust gas, and a primary superheater 14 for heating the boiler steam. Here, the primary superheater 14 is designed so that the inlet steam temperature is about 260 ° C. and the outlet steam temperature is 300 to 400 ° C. in order to prevent high-temperature corrosion.

On the other hand, a combustion gas suction port 15 is provided in the furnace wall 6 above the post-combustion stoker 5c, and a combustion gas discharge pipe 16 communicating with the combustion gas suction port 15 allows the main combustion chamber 7a to have a main combustion gas in the primary combustion chamber 7a. The combustion gas in the post-combustion section for post-combusting the burned refuse 2 is extracted. Then, the combustion gas extracted by the combustion gas discharge pipe 16 is connected to a dust collecting device 17 provided at the downstream end of the discharge pipe 16.
It is supplied to. Further, the downstream side of the dust collecting device 17 is connected to a combustion gas recirculation pipe 18 for recirculating the combustion gas after dust removal, and the downstream end of the combustion gas recirculation pipe 18 has a secondary combustion through a forced air blower 19. It is connected to the combustion gas outlet 20 on the upstream side of the air supply position. The combustion gas recirculation pipe 18 has a forced blower 19
An adjustment damper 21 is interposed on the upstream side of.

A secondary superheater 22 is inserted in the middle of the combustion gas recirculation pipe 18, and the steam that has exited the primary superheater 14 is subjected to the combustion gas after dust removal by the dust collector 17 in the secondary superheater 22. Thus, the steam is heated to 400 to 500 ° C.

Next, a specific example of the dust collector 17 will be described with reference to FIG. The dust collecting device 17
Is not limited to this structure, and various other embodiments are possible.

The dust collecting device 17 includes a casing 25 having an outer cylinder 23 having a cylindrical body and a cylindrical inner cylinder 24 provided concentrically inside the outer cylinder 23.
In the casing 25, a lid 26 is provided at an upper portion, and combustion gas introduction ports 27, 27 are provided at a portion between the outer cylinder 23 and the inner cylinder 24 of the lid 26, and at a lower portion, Annular hoppers 28, 28 having an inverted triangular cross section are provided at a portion sandwiched between the outer cylinder 23 and the inner cylinder 24,
A combustion gas outlet 29 for leading clean gas is provided inside the inner cylinder 24.

A plurality of cylindrical (or square) ceramic filters 3 are provided between the outer cylinder 23 and the inner cylinder 24.
0 is arranged. These ceramic filters 30
Are arranged radially in the horizontal direction about the center axis of the inner cylinder 24 and in multiple stages in the vertical direction. One end (outer end) of the ceramic filter 30 has its opening closed by a plug and only the other end (inner end) is opened. It is made to communicate with.

When dirty combustion gas (exhaust gas) containing dust is introduced from the combustion gas inlets 27, 27 in this manner,
This combustion gas passes through the pores of each ceramic filter 30 and enters the internal space of the ceramic filter 30.
The dust is filtered to become a clean gas, and is discharged from the combustion gas outlet 29 through the inner space of the inner cylinder 24 from the inner end, which is the opening end of the ceramic filter 30, to the outside of the system. In addition, a pulse tube 31 is provided in the inner space of the inner cylinder 24 so as to face a gas passage in each ceramic filter 30. By supplying air for backwashing to the pulse tube 31, Dust adhering to the outer surface and the pores of the filter 30 is regularly backwashed. Also,
The dust generated by this back washing is discharged out of the system from the annular hopper 28 by a conveyor (not shown).

In the incinerator 1 of the present embodiment configured as described above, first, the refuse 2 introduced from the hopper 3
It is sequentially supplied onto the drying stoker 5a by the pusher 4,
The drying stoker 5a is heated and dried by primary combustion air supplied from below and radiant heat from the primary combustion chamber 7a in a high temperature state. As a result, water and volatile components in the refuse 2 evaporate, and unburned gases such as CO and HC are released.

Thereafter, the refuse 2 that has passed through the drying stoker 5a and dried is burned on the combustion stoker 5b by the primary combustion air supplied from the air conduit 8b, and burns at the downstream end of the combustion stoker 8b. Reach the cut point.
Next, the refuse 2 is sent to a post-combustion stoker 5c, where the so-called ignited combustion is performed on the post-combustion stoker 5c by primary combustion air supplied from an air conduit 8c, and incinerated ash is taken out from an ash outlet 9. On the other hand, unburned gas and unburned matter generated due to the incineration of the refuse 2 are completely burned by the primary combustion air supplied from below the stoker 5 and the secondary combustion air supplied to the secondary combustion chamber 7b. It is discharged from the exhaust gas passage 12 through the outlet.

In the incinerator 1, the combustion gas (temperature: 60) in the post-combustion section above the post-combustion stoker 5c.
0 ° C. to 700 ° C.) is sucked from the combustion gas suction port 15 by the push-in blower 19 and supplied to the dust collector 17 through the combustion gas discharge pipe 16, and the dust in the combustion gas is collected by the dust collector 17. Is removed, the temperature is reduced by heat recovery by passing through the secondary superheater 22, and the combustion chamber 7 passes through the combustion gas recirculation pipe 18 from the outlet 20 on the upstream side of the secondary combustion air supply position. Supplied to Thus,
The combustion chamber upstream of the secondary combustion air supply position is agitated and mixed by blowing the combustion gas, and the composition of the combustion gas is reduced to a weak reducing atmosphere with a uniform composition distribution and temperature. Is completely burned, and CO and NO
The occurrence of _{X and the} like is greatly suppressed.

On the other hand, in the boiler 13 installed in the exhaust gas passage 12, the heat exchange with the exhaust gas
Of steam is generated, and this boiler steam is
4, the primary superheater 14 superheats the steam until the steam temperature becomes about 300 to 400 ° C.
Then, the superheated steam is passed through the steam pipe to the secondary superheater 22.
The secondary superheater 22 further heats the steam until the steam temperature reaches 400 to 500 ° C. Thereafter, the superheated steam is guided to a steam turbine (not shown), and the rotation of the steam turbine drives a generator to generate power.

According to the incinerator 1 of this embodiment, the combustion gas introduced from the dust collector 17 to the secondary superheater 22 contains no dust and has a low hydrogen chloride (HCl) concentration. However, there is no problem of pipe corrosion even if a special material is not used for the pipe of the secondary superheater 22 and the like. Moreover, since the steam is superheated by the combustion gas of the incinerator 1, the heat energy efficiency and the power generation efficiency can be improved without extra energy consumption. Also,
Since there is no problem of dust, the piping pitch of the secondary superheater 22 can be reduced, and the size of the superheater can be reduced.

FIG. 3 is a schematic configuration diagram of an incinerator according to another embodiment of the present invention.

In the above embodiment, the combustion gas after passing through the dust collector 17 is supplied to the combustion gas inlet 20 on the upstream side of the supply position of the secondary combustion air, and the combustion gas is supplied into the combustion chamber 7 by the combustion gas. However, in this embodiment, the combustion gas after passing through the dust collecting device 17 is mixed with the primary combustion air via the air conduits 8a and 8b and supplied into the primary combustion chamber 7a. It is configured so that Other than this, there is basically no difference from the previous embodiment. Therefore, the same reference numerals are given to the same parts as those in the previous embodiment, and the detailed description thereof will be omitted (the same applies to the following embodiments).

According to the present embodiment, after the oxygen-rich combustion gas extracted from the post-combustion section is removed by the dust collecting device 17, it is mixed with the primary combustion air upstream of the post-combustion section for combustion. Since it is supplied into the chamber 7, the amount of primary combustion air originally supplied to the primary combustion chamber can be reduced, and thus the amount of exhaust gas discharged from the incinerator can be reduced. This has the effect of contributing to downsizing of the exhaust gas treatment equipment disposed on the side.

FIG. 4 is a schematic configuration diagram of an incinerator according to still another embodiment of the present invention.

In each of the embodiments described above, the combustion gas is sucked from the post-combustion section of the incinerator. In this embodiment, the combustion gas suction port 32 is provided near the exhaust gas outlet above the secondary combustion chamber 7b. (Slightly downstream of the slag screen 33) (may be slightly upstream of the slag screen 33). With such a configuration, the same operation and effect as those of the above embodiments can be obtained. Also, if the configuration as in the present embodiment is adopted,
Since the amount of gas is larger than the amount of combustion gas in the post-combustion section, the amount of gas withdrawn by the combustion gas suction port 32 can be set freely. Further, the temperature of the drawing gas can be made higher (800 ° C. to 900 ° C.).

In this embodiment, the combustion gas after passing through the dust collecting device 17 is supplied to the combustion gas inlet 20 on the upstream side of the supply position of the secondary combustion air. As in the embodiment shown in FIG.
a, 8b and the primary combustion air mixed with the primary combustion air.
a.

In each of the above embodiments, the dust collector 17
Although the combustion gas after dust removal is passed through the secondary superheater in the above, an embodiment in which the combustion gas is passed through the primary superheater is also possible.

In each of the embodiments described above, the combustion gas extracted from the combustion chamber is recirculated to the combustion chamber after dust removal. However, since the combustion gas has a high temperature higher than a predetermined level, the white color of the exhaust gas is reduced. It can also be used for smoke control.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an incinerator according to an embodiment of the present invention.

FIG. 2 is a horizontal sectional view (a), an outer shape, and a vertical sectional view (b) of the dust collector.

FIG. 3 is a schematic configuration diagram of an incinerator according to another embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of an incinerator according to still another embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a conventional incinerator.

FIG. 6 is a configuration diagram of a conventional exhaust heat power generation system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Incinerator 2 Garbage 3 Hopper 4 Pusher 5 Stoker 5a Dry stoker 5b Combustion stoker 5c Post-combustion stoker 6 Furnace wall 7 Combustion chamber 7a Primary combustion chamber 7b Secondary combustion chamber 8 Primary combustion air supply device 8a-8c Air conduit 9 Ash exhaust Outlets 10a to 10c Adjustment damper 11 Secondary combustion air supply pipe 12 Exhaust gas passage 13 Boiler 14 Primary superheater 15, 32 Combustion gas suction port 17 Dust collector 18 Combustion gas recirculation pipe 22 Secondary superheater

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F23G 5/44 ZAB F23G 5/44 ZABF 5/46 ZAB 5/46 ZABA F23J 15/00 F23J 15/00 Z (72) Inventor Jin Akiyama 2-33, Kinrakuji-cho, Amagasaki-shi, Hyogo F-term in Takuma Co., Ltd. (reference) 3K061 HA06 HA17 HA19 HA27 HA29 3K065 AA02 AB01 AC01 BA01 JA05 JA13 JA18 3K070 DA06 DA07 DA32 DA49 DA50 DA76 3K078 AA01 BA03 BA22 CA03 CA06 CA12 CA21 CA22 CA24

Claims (5)

[Claims] 1. A primary combustion chamber for mainly burning an object to be burned with primary combustion air, and a secondary combustion chamber for completely burning unburned matter generated in the primary combustion chamber with secondary combustion air, In an incinerator comprising a primary combustion chamber and a post-combustion section for post-combustion of a substance to be combusted in the primary combustion chamber, the combustion gas extracted from the post-combustion section is introduced into a dust collector. A method for superheating steam in an incinerator, wherein the combustion gas after the dust has been removed by the dust collector is introduced into a superheater, and the superheater performs steam superheating. 2. An incinerator comprising: a primary combustion chamber for mainly burning an object to be burned by primary combustion air; and a secondary combustion chamber for completely burning unburned matter generated in the primary combustion chamber by secondary combustion air. In the method, the combustion gas extracted from the vicinity of the exhaust gas outlet above the secondary combustion chamber is introduced into a dust collector, and the combustion gas after dust has been removed by the dust collector is introduced into a superheater. A steam superheating method in an incinerator, wherein the steam is superheated by the method. 3. A primary superheater is provided in an exhaust gas passage of the incinerator, and the steam heated to a predetermined temperature by the primary superheater is guided to a superheater downstream of the dust collecting device. 3. A steam superheating method in the incinerator according to 2. 4. The incineration according to claim 1, wherein the combustion gas after passing through the superheater is supplied to an upstream side from a supply position of the secondary combustion air to agitate and mix the combustion chamber. Steam heating method in furnace. 5. The incineration according to claim 1, wherein the combustion gas after passing through the superheater is mixed with the primary combustion air and supplied to an upstream side of a post-combustion section in the primary combustion chamber. Steam heating method in furnace.