JP6351389B2 - Exhaust reburning system - Google Patents

Description

  The present invention relates to an exhaust gas reburning system in which a combustion burner that burns using combustion exhaust gas from a prime mover as an oxygen-containing gas is installed in a combustion chamber for heat recovery.

Such an exhaust reburning system is intended to improve the thermal efficiency by recovering the retained heat of the combustion exhaust gas discharged from the prime mover in a combustion chamber for heat recovery.
In the exhaust gas reburning system, for example, the prime mover is configured as a gas turbine for power generation that drives the generator, and the combustion chamber is configured as a combustion chamber of a steam boiler that generates steam to be supplied to the steam turbine for power generation. Thus, the present invention is applied to various systems such as being used to construct a so-called combined cycle power generation system.

  As a conventional example of an exhaust gas reburning system, a solid fuel pulverizer for pulverizing coal supplied from a solid fuel storage bin is provided, and a combustion burner uses coal pulverized by the solid fuel pulverizer (pulverized solid fuel) as fuel. Some are configured to burn (see, for example, Patent Document 1).

  In Patent Document 1, description of coal stored in the solid fuel storage bin and coal pulverized by the solid fuel crusher is omitted, but generally, the coal stored in the solid fuel storage bin is a lump. In addition, since the coal pulverized by the solid fuel pulverizer is in a granular form, it can be considered that the same applies to Patent Document 1.

  Patent Document 1 omits a detailed description of the solid fuel pulverizer, but describes that the combustion exhaust gas of a gas turbine as a prime mover is introduced to perform pulverization treatment, and the pulverization is performed. Coal (pulverized solid fuel) is configured to be supplied to the combustion burner in such a form that it is conveyed by the combustion exhaust gas of the gas turbine.

JP 2005-16750 A

Since the conventional exhaust gas reburning system is equipped with a solid fuel pulverizer that pulverizes massive coal into granular coal, the overall configuration is complicated and expensive, and improvement is desired. It was.
That is, since coal is cheaper than fuel oil such as heavy oil and fuel gas such as natural gas, it is desirable to use coal as a fuel. The overall configuration of the system is complicated and expensive, and improvement is desired.

  The present invention has been made in view of the above circumstances, and its object is to simplify and reduce the overall configuration while using coal as a fuel, and to change the amount of combustion. The object is to provide an exhaust gas reburning system that can be adjusted well.

In the exhaust gas reburning system of the present invention, a combustion burner that burns using combustion exhaust gas from a prime mover as an oxygen-containing gas is equipped in a combustion chamber for heat recovery, and the first characteristic configuration is
As the combustion burner, a coal combustion part that burns in the flue gas in a state where massive coal is placed and conveyed by a stoker, and a gas fuel or liquid fuel other than coal is burned in the flue gas and the amount of combustion is reduced. With other fuel combustion parts that can be changed and adjusted ,
The said other fuel combustion part is the point which is installed in the upper location rather than the said coal combustion part in the form which flows combustion gas toward the upper surface part of the said coal combustion part .
Incidentally, the gas fuel or liquid fuel other than the coal burned in the other fuel combustion section means a gas fuel or liquid fuel different from the bulk coal and the granular coal.

That is, the coal combustion section and the other fuel combustion section are equipped in the combustion chamber for heat recovery, and burn using the combustion exhaust gas from the prime mover as the oxygen-containing gas.
Since the coal burning part burns in a state where massive coal is placed and conveyed by a stoker, the massive coal can be supplied to the stoker and burned as it is. There is no need to equip a device for pulverization, and the overall configuration can be simplified and reduced in price.

The other fuel combustion section burns gas fuel or liquid fuel other than coal, and the amount of combustion can be changed and adjusted, so that the combustion of the other fuel combustion section depends on the fluctuation of the combustion load in the combustion chamber. The amount can be changed and adjusted.
In other words, since the coal combustion section burns massive coal as it is, it is difficult to appropriately change the combustion amount in accordance with fluctuations in the combustion load of the combustion chamber. In addition to this, by providing the other fuel combustion section that can satisfactorily adjust the amount of combustion, it is possible to satisfactorily adjust the amount of combustion according to fluctuations in the combustion load of the combustion chamber. .

  In short, according to the first characteristic configuration of the present invention, the exhaust gas reburning system can simplify and reduce the overall configuration while using coal as the fuel, and can perform the change adjustment of the combustion amount satisfactorily. Can provide.

Moreover , when the combustion gas of the other fuel combustion part flows toward the upper surface part of the coal combustion part, the upper surface part of the coal combustion part, that is, the massive coal placed and conveyed by the stoker is transferred to the other fuel combustion part. Thus, the coal combustion section can be burned well in a state where the air ratio is lowered.

  In other words, in order to burn the bulk coal placed and transported by the stalker, the air ratio is generally set to 1.1 or more. By heating with the combustion gas in the combustion section, for example, the massive coal placed and conveyed by the stoker can be burned well in a state where the air ratio is about 1.05.

  Therefore, by setting the supply amount of the combustion exhaust gas from the prime mover supplied as the oxygen-containing gas for combustion to the coal combustion section to the amount to be burned with the air ratio lowered, the exhaust gas is exhausted from the combustion chamber. This makes it possible to reduce the residual oxygen concentration of the exhaust gas, thereby improving the thermal efficiency.

  Incidentally, when the combustion gas of the other fuel combustion part flows toward the upper surface part of the coal combustion part, the residual oxygen contained in the combustion gas of the other fuel combustion part may be consumed as combustion oxygen for the coal combustion part. Also from this point, it is possible to reduce the residual oxygen concentration of the exhaust gas exhausted from the combustion chamber, and to improve the thermal efficiency.

In short, the first characteristic configuration of the present invention can provide an exhaust gas reburning system that can improve the thermal efficiency in addition to the above-described effects.

In addition to the first characteristic configuration described above, the second characteristic configuration of the exhaust gas reburning system of the present invention includes:
The combustion gas of the other fuel combustion unit is configured to flow toward a terminal end side in the conveying direction of the stalker in the upper surface of the coal combustion unit.

  That is, in the start end portion of the coal combustion portion in the stoker transport direction, the bulk coal dry distillation gas (volatile matter) is combusted. In view of the fact that massive coal (solid content) is combusted, the combustion gas of the other fuel combustion part is caused to flow toward the terminal side in the conveying direction of the stoker in the upper surface part of the coal combustion part. Thus, the combustion gas of the other fuel combustion section is sprayed on the massive coal after dry distillation.

  In this way, by blowing the combustion gas of the other fuel combustion section to the bulk coal after dry distillation, the bulk coal after dry distillation having low combustibility compared to the dry distillation gas (volatile matter) can be accurately burned. Therefore, as a result of being able to burn the entire bulk coal well, the calorific value of the coal burning part can be increased.

In short, the second characteristic configuration of the present invention can provide an exhaust reburning system capable of increasing the calorific value of the coal combustion section in addition to the operational effects of the first characteristic configuration.

In addition to the first or second characteristic configuration described above, the third characteristic configuration of the exhaust gas reburning system of the present invention includes:
The combustion exhaust gas from the prime mover is supplied to the other fuel combustion section in a state corresponding to the maximum combustion amount of the other fuel combustion section.

  That is, the combustion amount of the other fuel combustion part is changed and adjusted according to the fluctuation of the combustion load in the combustion chamber, but the combustion exhaust gas from the prime mover corresponds to the maximum combustion amount of the other fuel combustion part. Therefore, the supply amount of the combustion exhaust gas from the prime mover supplied as the oxygen-containing gas for combustion is insufficient regardless of the change adjustment of the combustion amount of the other fuel combustion portion. There is nothing.

  As described above, the supply amount of the combustion exhaust gas from the prime mover supplied as the oxygen-containing gas for combustion to the other fuel combustion unit is not deficient regardless of the change adjustment of the combustion amount of the other fuel combustion unit. Therefore, it is not necessary to provide a supply device (for example, a blower for combustion air) for supplying the oxygen-containing gas to the other fuel combustion section, thereby further simplifying and reducing the overall configuration. it can.

In short, according to the third characteristic configuration of the present invention, in addition to the operational effects of the first or second characteristic configuration , it is possible to provide an exhaust reburning system capable of further simplifying and reducing the overall configuration.

In addition to any of the first to third characteristic configurations described above, the fourth characteristic configuration of the exhaust gas reburning system of the present invention is
The prime mover is a gas turbine for power generation, and the combustion chamber is a combustion chamber of a steam boiler.

That is, while generating electricity with the gas turbine for power generation, the heat held by the combustion exhaust gas of the gas turbine can be recovered with the steam boiler, and steam can be generated while improving the thermal efficiency.
Incidentally, if a steam turbine for power generation is driven by steam generated by a steam boiler, a combined cycle power generation system can be configured.

In short, according to the fourth feature configuration of the present invention, in addition to the operational effects of any of the first to third feature configurations, the retained heat of the combustion exhaust gas of the gas turbine for power generation is recovered to improve the thermal efficiency. It is possible to provide an exhaust gas reburning system that can generate steam while achieving the above.

Schematic of combined cycle power generation system

Embodiment
Hereinafter, an embodiment when the exhaust gas reburning system of the present invention is applied to a combined cycle power generation system will be described with reference to the drawings.
(Overall configuration of combined cycle power generation system)
As shown in FIG. 1, the exemplified combined cycle power generation system includes a gas turbine 1 as a prime mover, a gas turbine side generator 2 driven by the gas turbine 1, and combustion exhaust gas from the gas turbine 1 as an oxygen-containing gas. A steam boiler E provided with a combustion burner B to be used, a steam turbine 3 driven by steam supplied from the steam boiler E, and a steam turbine side generator 4 driven by the steam turbine 3. Yes.

(Configuration of gas turbine)
The gas turbine 1 includes an air compression unit 1A, a combustor 1B, and a turbine unit 1C. In the present embodiment, the gas turbine-side generator 2 is connected to the air compression unit 1A.
The air compressing unit 1A is configured to rotate integrally with the turbine unit 1C, compress the air taken in through the air passage 5, and supply the compressed air to the combustor 1B.
The combustor 1B is configured to burn the fuel gas supplied through the fuel passage 6 with the compressed air supplied from the compression unit 1A, and the turbine unit 1C is rotationally driven by the combustion gas from the combustor 1B. It is comprised so that.

(Composition of steam boiler)
The steam boiler E includes a heat recovery combustion chamber N equipped with a combustion burner B, a steam generation water pipe section 7, and a steam superheat section 8 that superheats the steam generated in the steam generation water pipe section 7. Thus, the combustion gas from the combustion burner B is used to heat the steam superheating section 8 and the steam generating water pipe section 7 and supply the superheated steam from the steam superheating section 8 to the steam turbine 3.

Incidentally, the combustion gas from the combustion burner B is configured to be guided to the chimney 10 through the flue 9 after passing through the steam superheating portion 8 and the steam generating water pipe portion 7.
Further, steam after driving the steam turbine 3 is supplied to a water supply unit 11 including a condenser, a water supply tank, a water supply pump, and the like, so that the water supply unit 11 supplies water to the steam generation water pipe unit 7. It is configured.

(Combustion burner configuration)
As the combustion burner B, a coal combustion part Ba that burns in a state in which massive coal is placed and conveyed by the stoker 12, and another fuel combustion part that burns gas fuel or liquid fuel other than coal and can adjust the amount of combustion freely. Bb.
Incidentally, although illustration is omitted, in the present embodiment, a pair of left and right fuel combustion portions Bb are provided along the lateral width direction of the stoker 12.

(Details of coal combustion section)
The coal combustion unit Ba is supplied through the combustion exhaust gas supply port 14 while placing and transporting the massive coal input from the coal input port 13 from the start end side portion toward the end end portion in the transfer direction by the stoker 12. The gas turbine 1 is configured to burn with the combustion exhaust gas.
And it is comprised so that the residue after combustion may be discharged | emitted outside the combustion chamber N through the residue discharge port 15. FIG.

  The combustion exhaust gas of the gas turbine 1 supplied from the combustion exhaust gas supply port 14 flows upward while flowing in the lower space of the stoker 12 and is distributedly supplied over the entire conveying direction of the stoker 12. ing.

(Details of other fuel combustion section)
In the present embodiment, the other fuel combustion section Bb is configured to burn the fuel gas. Specifically, as the fuel gas, a city gas (for example, 13A) mainly composed of methane is used as the fuel gas. It is configured to burn as.

The other fuel combustion section Bb is provided with a fuel ejection section 17 that ejects fuel gas supplied through the fuel gas supply path 16 into the combustion chamber N.
The combustion exhaust gas of the gas turbine 1 received through the combustion exhaust gas inlet 18 flows to the front end side of the fuel injection part 17 through the gas flow space R around the fuel injection part 17 and is ejected from the fuel ejection part 17. The fuel gas is combusted by the combustion exhaust gas of the gas turbine 1.

  The fuel gas supply path 16 is provided with an on-off valve 19 for intermittently supplying the fuel gas and a fuel control valve 20 for adjusting the supply amount of the fuel gas to supply the fuel gas to be supplied to the other fuel combustion section Bb. By adjusting with the fuel control valve 20, it is comprised so that the combustion amount of the other fuel combustion part Bb can be changed and adjusted.

The other fuel combustion unit Bb is installed at a position above the coal combustion unit Ba in a state of being inclined downward to form a downward flame F, and the combustion gas G of the other fuel combustion unit Bb However, it is comprised so that it may flow toward the upper surface part of the coal combustion part Ba.
Specifically, the combustion gas G of the other fuel combustion section Bb is configured to flow toward the terminal portion in the conveying direction of the stoker 12 in the upper surface of the coal combustion section Ba.

Since the combustion gas G of the other fuel combustion part Bb flows toward the upper surface part of the coal combustion part Ba, the temperature of the coal placed and conveyed on the stoker 12 rises, so the air ratio is about 1.05. Coal can be burned.
Moreover, the combustion gas G of the other fuel combustion section Bb flows toward the terminal side in the conveying direction of the stalker 12 in the upper surface of the coal combustion section Ba, so that the solid content of the coal can be burned well. It is like that.

  That is, in the start side portion of the coal combustion part Ba in the conveying direction of the stoker 12, the bulk coal dry distillation gas (volatile matter) is combusted, and in the end side part of the coal combustion part Ba in the conveying direction of the stoker 12 The bulk coal (solid content) after dry distillation burns, but the combustion gas of the other fuel combustion section Bb is blown against the bulk coal after dry distillation, so that the dry coal gas (volatile matter) However, it is possible to accurately burn the bulk coal after dry distillation having low combustibility.

(About supply of combustion exhaust gas)
The combustion exhaust gas of the gas turbine 1 is distributed and supplied through the combustion exhaust gas supply passage 21 to the combustion exhaust gas supply port 14 of the coal combustion part Ba and the combustion exhaust gas inlet 18 of the other fuel combustion part Bb. .
In addition, although illustration is abbreviate | omitted, distribution which distributes the combustion exhaust gas of the gas turbine 1 to the combustion exhaust gas supply port 14 of the coal combustion part Ba, and the combustion exhaust gas inlet 18 of other fuel combustion part Bb in the combustion exhaust gas supply path 21 An adjustment mechanism to adjust the rate will be equipped.

  In the present embodiment, the combustion exhaust gas from the gas turbine 1 is supplied to the other fuel combustion unit Bb in a state corresponding to the maximum combustion amount of the other fuel combustion unit Bb, and the remaining part of the combustion exhaust gas from the gas turbine 1 Is configured to be supplied to the coal combustion section Ba.

  Incidentally, in this embodiment, although the case where the coal combustion part Ba and the other fuel combustion part Bb are burned using only the combustion exhaust gas from the gas turbine 1 is illustrated, for example, the coal combustion part Ba or the other fuel combustion part In addition to the combustion exhaust gas from the gas turbine 1, such as providing a blowing means for supplying combustion air to Bb, the combustion air is separately supplied to burn the coal combustion part Ba and the other fuel combustion part Bb. You may do it.

(Specific examples of the combustion amount of this embodiment)
In the present embodiment, the output of the gas turbine 1 is 5050 kW, and the combustion exhaust gas at about 500 ° C. is discharged by 57,100 m ³ N / H. The oxygen concentration of the combustion exhaust gas is, for example, 18 %.

Each of the pair of other fuel combustion sections Bb is burned with a maximum combustion amount of 12.25 million kcal / h, and the coal combustion section Ba is burned at a combustion amount of 3.5 million kcal / h.
The steam boiler E generates steam (superheated steam) having a temperature of 455 ° C. and a pressure of 5.98 MPaG at 50 t / h.

(Summary of embodiment)
The exhaust gas reburning system equipped in the above combined cycle power generation system burns the coal combustion part Ba equipped in the combustion chamber N for heat recovery in a state where massive coal is placed and conveyed by the stoker 12. Yes, the bulk coal can be supplied to the stoker 12 as it is and burnt, so there is no need to equip a device for crushing the bulk coal, thereby simplifying the overall structure and reducing the cost. Can be planned.

  And since the coal combustion part Ba burns lump coal with lump shape, according to the fluctuation | variation of the combustion load of the combustion chamber N (fluctuation | variation of steam production amount), what cannot change combustion amount appropriately However, since the fuel combustion unit Bb that can perform the change adjustment of the combustion amount satisfactorily is provided, the change adjustment of the combustion amount according to the fluctuation of the combustion load of the combustion chamber N can be performed well. It can be done.

  That is, the power generation amount of the steam turbine side generator 4 varies depending on the required power, and the combustion amount of the combustion burner B is adjusted in order to adjust the amount of steam supplied to the steam turbine 3 according to the variation. Although the change adjustment is performed, the combustion amount of the entire combustion burner B including the coal combustion portion Ba can be appropriately changed and adjusted by adjusting the combustion amount of the other fuel combustion portion Bb.

With the combustion gas of the other fuel combustion part Bb flowing toward the upper surface part of the coal combustion part Ba, the coal placed and transported by the stoker 12 is heated to reduce the air ratio, The combustion section can be burned well, and the residual oxygen contained in the combustion gas G of the other fuel combustion section Bb is consumed as combustion oxygen for the coal combustion section Ba. The residual oxygen concentration of the exhaust gas exhausted can be reduced.
When the oxygen concentration of the combustion exhaust gas from the gas turbine 1 is about 18%, for example, the residual oxygen concentration of the exhaust gas exhausted from the combustion chamber N can be made about 14 to 16%, for example. It becomes.

  Incidentally, since the combustion gas of the other fuel combustion part Bb flows toward the terminal side in the conveying direction of the stoker 12 in the upper surface part of the coal combustion part Ba, as described above, the coal after dry distillation Since the coal after dry distillation can be burned accurately by blowing the combustion gas of the other fuel burning section Bb on the other hand, as a result of being able to burn the entire coal well, the calorific value of the coal burning section Ba Can be raised.

  Since the combustion exhaust gas from the gas turbine 1 is supplied to the other fuel combustion unit Bb in a state corresponding to the maximum combustion amount of the other fuel combustion unit Bb, the combustion amount of the other fuel combustion unit Bb is reduced to the combustion chamber. Even if it is changed and adjusted according to the fluctuation of the combustion load of N, the supply amount of the combustion exhaust gas from the gas turbine 1 supplied as the oxygen-containing gas for combustion will not be insufficient. Therefore, it is not necessary to provide a supply device (for example, a blower for combustion air) for supplying the oxygen-containing gas, and the overall configuration can be further simplified and reduced in price.

[Another embodiment]
Next, another embodiment is listed.
(1) In the said embodiment, although the case where the other fuel combustion part Bb burned gas fuel as fuels other than coal was illustrated, liquid fuels, such as light oil and heavy oil, are burned as fuels other than coal May be implemented.

(2) In the said embodiment, although the gas turbine 1 was illustrated as a motor | power_engine, you may use various internal combustion engines, such as a gas engine and a diesel engine, as a motor | power_engine.

(3) In the said embodiment, although the combustion chamber N with which the steam boiler E was illustrated was illustrated, this invention is applicable to the combustion chamber N with which various heating furnaces are equipped.

(4) In the above embodiment, the case where the exhaust gas reburning system of the present invention is applied to a combined cycle power generation system has been exemplified. However, the exhaust gas reburning system of the present invention can be applied to various systems other than the combined cycle power generation system. Is.

  Note that the configurations disclosed in the above-described embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with the configurations disclosed in the other embodiments as long as no contradiction arises. The embodiment disclosed in this specification is an exemplification, and the embodiment of the present invention is not limited to this. The embodiment can be appropriately modified without departing from the object of the present invention.

1 prime mover 12 stalker B combustion burner Ba coal combustion part Bb other fuel combustion part G combustion gas E steam boiler N combustion chamber

Claims (4)

A combustion burner that burns using combustion exhaust gas from a prime mover as an oxygen-containing gas is an exhaust gas reburning system equipped in a combustion chamber for heat recovery,
As the combustion burner, a coal combustion part that burns in the flue gas in a state where massive coal is placed and conveyed by a stoker, and a gas fuel or liquid fuel other than coal is burned in the flue gas and the amount of combustion is reduced. With other fuel combustion parts that can be changed and adjusted ,
An exhaust reburning system in which the other fuel combustion section is installed at a location above the coal combustion section in a form in which combustion gas flows toward the upper surface of the coal combustion section . 2. The exhaust gas reburning system according to claim 1 , wherein the combustion gas of the other fuel combustion unit is configured to flow toward a terminal side portion in a conveying direction of the stalker in an upper surface portion of the coal combustion unit . The exhaust gas reburning system according to claim 1 or 2 , wherein the combustion exhaust gas from the prime mover is supplied to the other fuel combustion section in a state corresponding to the maximum combustion amount of the other fuel combustion section . The exhaust gas reburning system according to any one of claims 1 to 3, wherein the prime mover is a gas turbine for power generation, and the combustion chamber is a combustion chamber of a steam boiler .

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