WO2011055814A1 - ボイラ - Google Patents
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- WO2011055814A1 WO2011055814A1 PCT/JP2010/069792 JP2010069792W WO2011055814A1 WO 2011055814 A1 WO2011055814 A1 WO 2011055814A1 JP 2010069792 W JP2010069792 W JP 2010069792W WO 2011055814 A1 WO2011055814 A1 WO 2011055814A1
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- WIPO (PCT)
- Prior art keywords
- bypass
- boiler
- predetermined value
- bypass duct
- furnace
- Prior art date
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/006—Layout of treatment plant
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8621—Removing nitrogen compounds
- B01D53/8625—Nitrogen oxides
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
- F23L11/00—Arrangements of valves or dampers after the fire
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
- F23L15/00—Heating of air supplied for combustion
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J2215/00—Preventing emissions
- F23J2215/10—Nitrogen; Compounds thereof
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J2900/00—Special arrangements for conducting or purifying combustion fumes; Treatment of fumes or ashes
- F23J2900/11001—Conducting systems with a gas flow bypass from main flue to an auxiliary flue
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2235/00—Valves, nozzles or pumps
- F23N2235/02—Air or combustion gas valves or dampers
- F23N2235/04—Air or combustion gas valves or dampers in stacks
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2237/00—Controlling
- F23N2237/20—Controlling one or more bypass conduits
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery
Definitions
- the present invention relates to a boiler provided with a denitration device for removing NOx in boiler exhaust gas generated in a furnace.
- Patent Document 1 As a boiler provided with a denitration device that removes NOx in boiler exhaust gas generated in a furnace, for example, one disclosed in Patent Document 1 is known.
- Patent Document 1 what is disclosed in Patent Document 1 is installed in, for example, an ironworks, and a boiler furnace using by-product gas (blast furnace gas, converter gas, etc.) generated in the production process of the ironworks as a fuel for mixed combustion
- by-product gas blast furnace gas, converter gas, etc.
- the boiler exhaust gas generated in the furnace increases as the mixed firing rate increases. Therefore, the rotational speed (output) of the induction fan that attracts (suctions) the boiler exhaust gas and sends (discharges) it to the chimney must be increased along with the increase of the mixed combustion rate.
- the draft pressure at the inlet of the induction fan May fall below the lower limit of operation of the electrostatic precipitator, making it impossible to operate (operate).
- the present invention has been made in view of the above circumstances, and uses a by-product gas generated in the production process of an ironworks as a fuel for co-firing, and even if the co-firing rate increases, it is disposed downstream of the denitration device.
- a first aspect of the present invention includes a furnace, a economizer, a denitration device, and an air preheater, and by-product gas generated in the production process of the steel works is input to the furnace as a fuel for co-firing.
- a bypass duct that bypasses the denitration device, a bypass damper that is provided in the middle of the bypass duct and opens and closes a flow path in the bypass duct, and a mixed firing rate
- a controller that fully closes the bypass damper when the value is lower than a predetermined value, and fully opens the bypass damper when the co-firing ratio is equal to or higher than a predetermined value.
- the boiler exhaust gas when the mixed combustion rate is lower than a predetermined value, that is, when the NOx concentration is high, the boiler exhaust gas is denitrated through the denitration device without passing through the bypass duct,
- the mixed combustion rate is equal to or higher than a predetermined value, that is, when the NOx concentration is low, the boiler exhaust gas is guided to the downstream side through a bypass duct having a small pipe line (flow path) resistance.
- a predetermined value that is, when the NOx concentration is low
- the boiler exhaust gas is guided to the downstream side through a bypass duct having a small pipe line (flow path) resistance.
- the draft pressure at the inlet of the induction fan located downstream of the air preheater is predetermined. It is possible to maintain an electric dust collector arranged on the downstream side of the air preheater, and to adopt an air preheater, a duct, etc. having a pressure strength comparable to the conventional one. And an increase in manufacturing cost can be suppressed.
- a thermal power plant includes the boiler, an electric dust collector, an induction fan, a steam turbine, a generator, and a chimney.
- the thermal power plant when the mixed combustion rate is lower than a predetermined value, that is, when the NOx concentration is high, the boiler exhaust gas passes through the denitration device without passing through the bypass duct.
- the mixed combustion rate is equal to or higher than the predetermined value, that is, when the NOx concentration is low, the boiler exhaust gas is led to the downstream side through the bypass duct having a small pipe line (flow path) resistance.
- the draft pressure at the inlet of the induction fan located downstream of the air preheater is predetermined. It is possible to maintain an electric dust collector installed on the downstream side of the air preheater, and to use an air preheater, electric precipitator, duct, etc. with the same pressure resistance as before. It is possible to suppress the increase in manufacturing cost.
- a third aspect of the present invention includes a furnace, a economizer, a denitration device, an air preheater, a bypass duct that bypasses the denitration device, and is provided in the middle of the bypass duct.
- a by-pass damper that opens and closes the flow path of the boiler, and the operation method of the boiler configured to allow the by-product gas generated in the production process of the steel mill to be input to the furnace as a fuel for mixed combustion.
- the bypass damper is fully closed when the mixed firing rate is lower than a predetermined value, and the bypass damper is fully opened when the mixed firing rate is equal to or higher than the predetermined value.
- the boiler exhaust gas when the mixed combustion rate is lower than a predetermined value, that is, when the NOx concentration is high, the boiler exhaust gas does not pass through the bypass duct but passes through the denitration device.
- the mixed combustion rate is equal to or higher than a predetermined value, that is, when the NOx concentration is low
- the boiler exhaust gas is led to the downstream side through a bypass duct having a small pipe line (flow path) resistance.
- the draft pressure at the inlet of the induction fan located downstream of the air preheater is predetermined. It is possible to maintain an electric dust collector arranged on the downstream side of the air preheater, and to adopt an air preheater, a duct, etc. having a pressure strength comparable to the conventional one. And an increase in manufacturing cost can be suppressed.
- a furnace, a economizer, a denitration device, an air preheater, a bypass duct that bypasses the denitration device, and a passage in the bypass duct are provided in the middle of the bypass duct.
- a boiler that is provided with a bypass damper that opens and closes, and that is configured so that by-product gas generated in the production process of the steel works can be input to the furnace as a fuel for mixed combustion, an electric dust collector, and an induction fan
- An operation method of a thermal power plant comprising a steam turbine, a generator, and a chimney, and when the mixed combustion rate is lower than a predetermined value, the bypass damper is fully closed, and the mixed combustion rate is a predetermined value. In the above case, the bypass damper is fully opened.
- the boiler exhaust gas when the mixed combustion rate is lower than a predetermined value, that is, when the NOx concentration is high, the boiler exhaust gas does not pass through the bypass duct and the denitration device is used.
- the NOx concentration is higher than a predetermined value, that is, when the NOx concentration is low, the boiler exhaust gas is led to the downstream side through a bypass duct having a small pipe line (flow path) resistance.
- the draft pressure at the inlet of the induction fan located downstream of the air preheater is predetermined. It is possible to maintain an electric dust collector installed on the downstream side of the air preheater, and to use an air preheater, electric precipitator, duct, etc. with the same pressure resistance as before. It is possible to suppress the increase in manufacturing cost.
- the by-product gas generated in the production process of the steel works is used as a fuel for mixed combustion, and even when the mixed combustion rate increases, the electrostatic precipitator disposed on the downstream side of the denitration device Therefore, it is not necessary to increase the pressure strength of an air preheater, a duct, or the like disposed on the downstream side of the denitration apparatus, and an increase in manufacturing cost can be suppressed.
- FIG. 1 is a schematic system diagram of a thermal power plant including a boiler according to an embodiment of the present invention. It is a graph which shows the relationship between the opening-and-closing state of the bypass damper shown in FIG. 1, the draft pressure in the entrance of an induction fan, and a mixed-burning rate. 3 is a chart showing the relationship between the open / closed state of the bypass damper shown in FIG. 1, the NOx concentration, and the mixed combustion rate.
- FIG. 1 is a schematic system diagram of a thermal power plant equipped with a boiler according to the present embodiment.
- the boiler 1 according to the present embodiment includes a furnace 2, an economizer 3, a denitration device 4, and an air preheater (air pre-heater) 5.
- the thermal power plant 20 according to the present embodiment includes a boiler 1, an electrostatic precipitator 6, an induction draft fan 7, a steam turbine (not shown), and a generator. (Not shown) and a chimney 8 are provided.
- the denitration apparatus 4 is an apparatus that decomposes NOx into harmless nitrogen and water by mixing ammonia into the boiler exhaust gas containing NOx, which is generated in the furnace 2 and sent from the economizer 3, and passes through the catalyst layer. is there.
- symbols 9 and 10 in FIG. 1 are NOx meters which each measure the NOx density
- the furnace 2, the economizer 3, the air preheater 5, the electrostatic precipitator 6, the induction ventilator 7, the steam turbine, the generator, and the chimney 8 are all the same as those conventionally employed. The description is omitted here.
- a bypass duct 11 that bypasses (detours) the denitration device 4 is provided, and a bypass damper 12 that opens and closes a flow path in the bypass duct 11 is provided in the middle of the bypass duct 11.
- the bypass damper 12 is operated by a controller 13, and the controller 13 is operated based on a BFG (Blast Furnace Gas) mixed firing rate (see FIGS. 2 and 3).
- BFG Blast Furnace Gas
- downstream of the NOx meter 9 and upstream of the branch point 15 to which the upstream end of the bypass duct 11 is connected downstream of the NOx meter 9 and upstream of the branch point 15 to which the upstream end of the bypass duct 11 is connected.
- GMF Gas Mixing Fan
- the controller 13 switches the furnace 2 from heavy oil mono-combustion (BFG mixed combustion rate 0%) to mixed combustion of heavy oil and BFG (fuel gas generated in a blast furnace at a steelworks (blast furnace gas)).
- BFG mixed combustion rate is increased, and the draft pressure at the inlet of the induction fan 7 becomes, for example, the operation lower limit value of the electric dust collector 6 +0.5 kPa (until the BFG mixed firing rate is 32% in the present embodiment).
- the bypass damper 12 is fully closed, and when the operation lower limit value of the electrostatic precipitator 6 reaches +0.5 kPa, the bypass damper 12 is fully opened.
- the controller 13 reduces the BFG mixed combustion rate, and the draft pressure at the inlet of the induction fan 7 causes the bypass damper 12 to be fully closed, for example.
- the bypass damper 12 is fully opened until the operation lower limit value +0.8 kPa of the electric dust collector 6 can be secured (until the BFG mixed firing rate becomes 29% in this embodiment), and the bypass damper 12 is When the operation lower limit value +0.8 kPa of the electric dust collector 6 can be secured when fully closed, the bypass damper 12 is fully opened.
- the denitration apparatus 4 is operated (operated). That is, ammonia is sprayed into the denitration device 4.
- the BFG co-firing rate is high and the NOx concentration is not so high (the NOx concentration is about 35 ppm lower than the regulation value (for example, 130 ppm)).
- the operation of the denitration apparatus 4 is stopped. That is, spraying of ammonia into the denitration device 4 is stopped.
- the BFG co-firing rate is the ratio of BFG to the fuel (heavy oil and BFG) charged into the furnace 2, and is calculated on a calorie basis.
- the calorie per 1 Nm 3 of BFG is about 800 kcal.
- the mixed combustion rate is a predetermined value (for example, 32% in the case where the BFG mixed combustion rate is increased by switching from the heavy oil exclusive combustion to the mixed combustion of heavy oil and BFG, and the heavy oil and BFG.
- the BFG co-firing rate is reduced to 29%), that is, when the NOx concentration is high, the boiler exhaust gas does not pass through the bypass duct 11 when switching from co-firing to heavy oil mono-combustion.
- the mixed combustion rate is equal to or higher than the predetermined value, that is, when the NOx concentration is low, the boiler exhaust gas is guided downstream through the bypass duct 11 having a low duct (flow path) resistance. .
- the draft pressure at the inlet of the induction fan 7 located downstream of the air preheater 5 is set to a predetermined value.
- Value for example, the lower limit of operation of the electrostatic precipitator 6 +0.5 kPa
- the air preheater 5, the duct 14, etc. which have comparable pressure-resistant intensity
- the mixed combustion rate is changed to a predetermined value (for example, 32 when the BFG mixed combustion rate is increased by switching from heavy oil exclusive combustion to mixed combustion of heavy oil and BFG). %, When switching from mixed combustion of heavy oil and BFG to heavy oil exclusive combustion, the BFG mixed combustion rate is lower than 29%), that is, when the NOx concentration is high, the boiler exhaust gas passes through the bypass duct 11. If the NOx concentration is not less than the predetermined value, that is, if the NOx concentration is low, the boiler exhaust gas passes downstream of the bypass duct 11 having a low pipe line (channel) resistance. Will be guided.
- a predetermined value for example, 32 when the BFG mixed combustion rate is increased by switching from heavy oil exclusive combustion to mixed combustion of heavy oil and BFG.
- the BFG mixed combustion rate is lower than 29%), that is, when the NOx concentration is high, the boiler exhaust gas passes through the bypass duct 11. If the NOx concentration is not less than the predetermined value, that is, if the NOx concentration is low, the boiler exhaust gas passes
- by-product gas for example, BFG
- BFG by-product gas
- the draft pressure at the inlet of the electric dust collector can be maintained at a predetermined value (for example, the lower limit of operation of the electrostatic precipitator 6 +0.5 kPa) or more, and the electrostatic precipitator 6 disposed downstream of the air preheater 5 is operated.
- the air preheater 5, the electrostatic precipitator 6, the duct 14, and the like having the same pressure resistance as the conventional one can be employed, and an increase in manufacturing cost can be suppressed.
- the thermal power plant 20 when the furnace 2 is switched from the mixed combustion of heavy oil and BFG to the dedicated combustion of heavy oil, the BFG mixed combustion rate is reduced, and the draft pressure at the inlet of the induction fan 7 is
- the bypass damper 12 when the bypass damper 12 is fully closed, the operation lower limit value +0.8 kPa of the electrostatic precipitator 6 can be secured, that is, switching from heavy oil exclusive combustion to mixed combustion of heavy oil and BFG, Is set to be higher than a predetermined value (the operation lower limit value of the electrostatic precipitator 6 +0.5 kPa) when the bypass damper 12 is operated from fully closed to fully open.
- a predetermined value the operation lower limit value of the electrostatic precipitator 6 +0.5 kPa
- the thermal power plant 20 when the bypass duct 11 is opened, the boiler exhaust gas is guided to the downstream side through the bypass duct 11 having a small pipe line (channel) resistance. Become. Thereby, the induction fan 7 which has the output comparable as the past can be employ
- the mixed combustion rate is a predetermined value (for example, 32% in the case where the BFG mixed combustion rate is increased by switching from the heavy oil exclusive combustion to the mixed combustion of heavy oil and BFG, When switching from the mixed combustion of heavy oil and BFG to the dedicated combustion of heavy oil, if the BFG mixed combustion rate is lower than 29%), that is, if the NOx concentration is high, the boiler exhaust gas does not pass through the bypass duct 11
- the NOx concentration is higher than a predetermined value, that is, when the NOx concentration is low, the boiler exhaust gas is led to the downstream side through the bypass duct 11 having a small pipe line (channel) resistance. It will be.
- the draft pressure at the inlet of the induction fan 7 located downstream of the air preheater 5 is set to a predetermined value.
- Value for example, the operation lower limit value of the electrostatic precipitator 6 +0.5 kPa
- the air preheater 5, the duct 14, etc. which have comparable pressure-resistant intensity
- the mixed combustion rate is changed to a predetermined value (for example, 32 when the BFG mixed combustion rate is increased by switching from heavy oil exclusive combustion to mixed combustion of heavy oil and BFG). %, When switching from mixed combustion of heavy oil and BFG to heavy oil exclusive combustion, the BFG mixed combustion rate is lower than 29%), that is, when the NOx concentration is high, the boiler exhaust gas passes through the bypass duct 11. If the NOx concentration is not less than the predetermined value, that is, if the NOx concentration is low, the boiler exhaust gas passes downstream of the bypass duct 11 having a low pipe line (channel) resistance. Will be guided.
- by-product gas for example, BFG
- BFG by-product gas
- the draft pressure at the inlet of the electric dust collector can be maintained at a predetermined value (for example, the operation lower limit value of the electric dust collector 6 +0.5 kPa) or more, and the electric dust collector 6 disposed on the downstream side of the air preheater 5 is operated.
- the air preheater 5, the electrostatic precipitator 6, the duct 14, and the like having the same pressure resistance as the conventional one can be employed, and an increase in manufacturing cost can be suppressed.
- the operating method of the thermal power plant 20 when the furnace 2 is switched from the mixed combustion of heavy oil and BFG to the dedicated combustion of heavy oil, the BFG mixed combustion rate is lowered and the draft at the inlet of the induction fan 7 is reduced.
- the pressure is, for example, when the bypass damper 12 is fully closed, the operation lower limit value +0.8 kPa of the electrostatic precipitator 6 can be secured, that is, the heavy oil exclusive firing is switched to the mixed combustion of heavy oil and BFG,
- the BFG mixed firing rate is increased, and is set to be higher than a predetermined value (the operation lower limit value of the electrostatic precipitator 6 +0.5 kPa) when the bypass damper 12 is operated from fully closed to fully opened.
- a predetermined value the operation lower limit value of the electrostatic precipitator 6 +0.5 kPa
- the induction fan 7 which has the output comparable as the past can be employ
- adopted the enlargement of the induction fan 7 can be avoided, and the increase in manufacturing cost can be suppressed.
- the present invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the gist of the present invention.
- the mixed combustion of heavy oil and BFG has been described as a specific example, but the present invention is not limited to this, and gaseous fuel obtained by gasifying coal instead of heavy oil or Natural gas or coal gas (COG, coke oven gas) may be used, and LDG (converter gas (fuel gas) generated in a steelworks converter) may be used instead of BFG.
- COG Natural gas or coal gas
- LDG converter gas (fuel gas) generated in a steelworks converter)
- the calorie per 1 Nm 3 of LDG is about 2000 kcal.
- bypass damper 12 when the bypass damper 12 is fully opened in the middle of the duct 14 located on the upstream side of the denitration device 4 and downstream of the branch point 15, the flow path in the duct 14 is closed, and the bypass damper 12 is fully closed. At this time, it is more preferable that a damper (not shown) that opens the flow path in the duct 14 is provided. Thereby, when the operation of the denitration device 4 is stopped, the inflow of boiler exhaust gas to the denitration device 4 is surely prevented, and clogging of the catalyst layer due to ash contained in the boiler exhaust gas can be prevented. it can.
- damper provided in the middle of the bypass damper 12 and the duct 14 is not used only in the fully open or fully closed state, but is used in an intermediate position between the fully open and fully closed as appropriate. You can also
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Abstract
Description
また、誘引通風機の入口におけるドラフト圧の低下に耐え得るよう、脱硝装置の下流側に配置される空気予熱器、電気集塵装置、ダクト等の耐圧強度を高めなければならず、製造コストが嵩んでしまうといった問題点もあった。
本発明の第1の態様は、火炉と、節炭器と、脱硝装置と、空気予熱器とを備え、前記火炉に、製鉄所の生産過程において発生する副生ガスを混焼用の燃料として投入することができるように構成されたボイラであって、前記脱硝装置をバイパスするバイパスダクトと、前記バイパスダクトの途中に設けられて、前記バイパスダクト内の流路を開閉するバイパスダンパと、混焼率が所定値よりも低い場合に、前記バイパスダンパを全閉とし、混焼率が所定値以上の場合に、前記バイパスダンパを全開とする制御器とを備えている。
これにより、製鉄所の生産過程において発生する副生ガスを混焼用の燃料として使用し、混焼率が増加した場合でも、空気予熱器の下流側に位置する誘引通風機の入口におけるドラフト圧を所定値以上に保つことができ、空気予熱器の下流側に配置される電気集塵装置を運用することができるとともに、従来と同程度の耐圧強度を有する空気予熱器、ダクト等を採用することができ、製造コストの増加を抑制することができる。
これにより、製鉄所の生産過程において発生する副生ガスを混焼用の燃料として使用し、混焼率が増加した場合でも、空気予熱器の下流側に位置する誘引通風機の入口におけるドラフト圧を所定値以上に保つことができ、空気予熱器の下流側に配置される電気集塵装置を運用することができるとともに、従来と同程度の耐圧強度を有する空気予熱器、電気集塵機、ダクト等を採用することができ、製造コストの増加を抑制することができる。
これにより、製鉄所の生産過程において発生する副生ガスを混焼用の燃料として使用し、混焼率が増加した場合でも、空気予熱器の下流側に位置する誘引通風機の入口におけるドラフト圧を所定値以上に保つことができ、空気予熱器の下流側に配置される電気集塵装置を運用することができるとともに、従来と同程度の耐圧強度を有する空気予熱器、ダクト等を採用することができ、製造コストの増加を抑制することができる。
これにより、製鉄所の生産過程において発生する副生ガスを混焼用の燃料として使用し、混焼率が増加した場合でも、空気予熱器の下流側に位置する誘引通風機の入口におけるドラフト圧を所定値以上に保つことができ、空気予熱器の下流側に配置される電気集塵装置を運用することができるとともに、従来と同程度の耐圧強度を有する空気予熱器、電気集塵機、ダクト等を採用することができ、製造コストの増加を抑制することができる。
図1に示すように、本実施形態に係るボイラ1は、火炉2と、節炭器(Economizer)3と、脱硝装置4と、空気予熱器(Air Pre-Heater)5とを備えている。また、本実施形態に係る火力発電プラント20は、ボイラ1と、電気集塵装置(Electrostatic Precipitator)6と、誘引通風機(Induced Draft Fan)7と、蒸気タービン(図示せず)と、発電機(図示せず)と、煙突8とを備えている。
なお、図1中の符号9,10はそれぞれ、排ガス中のNOx濃度を測定するNOx計である。
また、火炉2、節炭器3、空気予熱器5、電気集塵装置6、誘引通風機7、蒸気タービン、発電機、煙突8は、いずれも従来採用されているものと同じであるので、ここではその説明を省略する。
また、節炭器3から送出されたボイラ排ガスを脱硝装置4に導くダクト14の途中で、NOx計9よりも下流側、バイパスダクト11の上流端が接続された分岐点15よりも上流側には、節炭器3から送出されたボイラ排ガスの一部を火炉2に導くダクト16が設けられている。ダクト16の途中には、図示しないGMF(Gas Mixing Fan:ガス混合通風機)が設けられており、GMFから送出されたボイラ排ガスは、燃焼用空気とともに火炉2内に再投入される。
一方、制御器13は、火炉2が重油とBFGとの混焼から重油専焼に切り替えられる際、BFG混焼率が低められ、誘引通風機7の入口におけるドラフト圧が、例えば、バイパスダンパ12を全閉としたときに、電気集塵装置6の運用下限値+0.8kPaを確保することができるまで(本実施形態ではBFG混焼率が29%になるまで)バイパスダンパ12を全開とし、バイパスダンパ12を全閉としたときに、電気集塵装置6の運用下限値+0.8kPaを確保することができるようになったらバイパスダンパ12を全開とする。
一方、バイパスダンパ12が全開とされている場合には、BFG混焼率が高く、NOx濃度もさほど高くない(NOx濃度が規制値(例えば、130ppm)よりも約35ppm程度低くなる)ため、図3に示すように、脱硝装置4の運転を停止する。すなわち、脱硝装置4内へのアンモニアの噴霧を停止する。
ここで、BFG混焼率とは、火炉2に投入される燃料(重油およびBFG)のうち、BFGが占める割合のことであり、カロリベースに算出されたものである。また、BFGの1Nm3当たりのカロリは約800kcalである。
これにより、製鉄所の生産過程において発生するBFGを混焼用の燃料として使用し、混焼率が増加した場合でも、空気予熱器5の下流側に位置する誘引通風機7の入口におけるドラフト圧を所定値(例えば、電気集塵装置6の運用下限値+0.5kPa)以上に保つことができ、空気予熱器5の下流側に配置される電気集塵装置6を運用することができるとともに、従来と同程度の耐圧強度を有する空気予熱器5、ダクト14等を採用することができ、製造コストの増加を抑制することができる。
これにより、製鉄所の生産過程において発生する副生ガス(例えば、BFG)を混焼用の燃料として使用し、混焼率が増加した場合でも、空気予熱器5の下流側に位置する誘引通風機7の入口におけるドラフト圧を所定値(例えば、電気集塵装置6の運用下限値+0.5kPa)以上に保つことができ、空気予熱器5の下流側に配置される電気集塵装置6を運用することができるとともに、従来と同程度の耐圧強度を有する空気予熱器5、電気集塵装置6、ダクト14等を採用することができ、製造コストの増加を抑制することができる。
これにより、誘引通風機7の入口におけるドラフト圧が電気集塵装置6の運用下限値を下回ることを確実に防止することができ、プラント全体の安全性を向上させることができる。
これにより、従来と同程度の出力を有する誘引通風機7を採用することができ、誘引通風機7の大型化を回避することができ、製造コストの増加を抑制することができる。
これにより、製鉄所の生産過程において発生するBFGを混焼用の燃料として使用し、混焼率が増加した場合でも、空気予熱器5の下流側に位置する誘引通風機7の入口におけるドラフト圧を所定値(例えば、電気集塵装置6の運用下限値+0.5kPa)以上に保つことができ、空気予熱器5の下流側に配置される電気集塵装置6を運用することができるとともに、従来と同程度の耐圧強度を有する空気予熱器5、ダクト14等を採用することができ、製造コストの増加を抑制することができる。
これにより、製鉄所の生産過程において発生する副生ガス(例えば、BFG)を混焼用の燃料として使用し、混焼率が増加した場合でも、空気予熱器5の下流側に位置する誘引通風機7の入口におけるドラフト圧を所定値(例えば、電気集塵装置6の運用下限値+0.5kPa)以上に保つことができ、空気予熱器5の下流側に配置される電気集塵装置6を運用することができるとともに、従来と同程度の耐圧強度を有する空気予熱器5、電気集塵装置6、ダクト14等を採用することができ、製造コストの増加を抑制することができる。
これにより、誘引通風機7の入口におけるドラフト圧が電気集塵装置6の運用下限値を下回ることを確実に防止することができ、プラント全体の安全性を向上させることができる。
これにより、従来と同程度の出力を有する誘引通風機7を採用することができ、誘引通風機7の大型化を回避することができ、製造コストの増加を抑制することができる。
例えば、上述した実施形態では、重油とBFGとの混焼を一具体例として挙げて説明したが、本発明はこれに限定されるものではなく、重油の代わりに石炭をガス化させた気体燃料や天然ガスあるいは石炭ガス(COG、コーク・オーブン・ガス)を用い、BFGの代わりにLDG(製鉄所の転炉において発生した転炉ガス(燃料ガス))を用いるようにすることもできる。なお、LDGの1Nm3当たりのカロリは約2000kcalである。
これにより、脱硝装置4の運転が停止されている場合には、ボイラ排ガスの脱硝装置4への流入が確実に防止され、ボイラ排ガス中に含まれる灰による触媒層の目詰まりを防止することができる。
2 火炉
3 節炭器
4 脱硝装置
5 空気予熱器
6 電気集塵装置
7 誘引通風機
8 煙突
11 バイパスダクト
12 バイパスダンパ
13 制御器
20 火力発電プラント
Claims (4)
- 火炉と、節炭器と、脱硝装置と、空気予熱器とを備え、前記火炉に、製鉄所の生産過程において発生する副生ガスを混焼用の燃料として投入することができるように構成されたボイラであって、
前記脱硝装置をバイパスするバイパスダクトと、
前記バイパスダクトの途中に設けられて、前記バイパスダクト内の流路を開閉するバイパスダンパと、
混焼率が所定値よりも低い場合に、前記バイパスダンパを全閉とし、混焼率が所定値以上の場合に、前記バイパスダンパを全開とする制御器とを備えていることを特徴とするボイラ。 - 請求項1に記載のボイラと、電気集塵装置と、誘引通風機と、蒸気タービンと、発電機と、煙突とを備えていることを特徴とする火力発電プラント。
- 火炉と、節炭器と、脱硝装置と、空気予熱器と、前記脱硝装置をバイパスするバイパスダクトと、このバイパスダクトの途中に設けられて、前記バイパスダクト内の流路を開閉するバイパスダンパとを備え、前記火炉に、製鉄所の生産過程において発生する副生ガスを混焼用の燃料として投入することができるように構成されたボイラの運転方法であって、
混焼率が所定値よりも低い場合に、前記バイパスダンパを全閉とし、混焼率が所定値以上の場合に、前記バイパスダンパを全開とするようにしたことを特徴とするボイラの運転方法。 - 火炉、節炭器、脱硝装置、空気予熱器、前記脱硝装置をバイパスするバイパスダクト、および前記バイパスダクトの途中に設けられて、前記バイパスダクト内の流路を開閉するバイパスダンパを備え、前記火炉に、製鉄所の生産過程において発生する副生ガスを混焼用の燃料として投入することができるように構成されたボイラと、電気集塵装置と、誘引通風機と、蒸気タービンと、発電機と、煙突とを備えてなる火力発電プラントの運転方法であって、
混焼率が所定値よりも低い場合に、前記バイパスダンパを全閉とし、混焼率が所定値以上の場合に、前記バイパスダンパを全開とするようにしたことを特徴とする火力発電プラントの運転方法。
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JPS5517019A (en) * | 1978-07-19 | 1980-02-06 | Kobe Steel Ltd | Dry denitration method |
JPS5955234U (ja) * | 1983-08-01 | 1984-04-11 | バブコツク日立株式会社 | 燃焼装置 |
JPH08258980A (ja) * | 1995-03-27 | 1996-10-08 | Nippon Steel Corp | ホッパ内粉粒体の搬送状況判定方法および装置 |
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JPS61240007A (ja) * | 1985-04-17 | 1986-10-25 | Mitsubishi Heavy Ind Ltd | 混焼ボイラ |
CN2221155Y (zh) * | 1994-12-23 | 1996-02-28 | 姜桂荣 | 涡流式烟气净化器 |
JP3856589B2 (ja) * | 1999-04-20 | 2006-12-13 | 株式会社タクマ | 燃焼設備 |
JP2003236334A (ja) * | 2002-02-19 | 2003-08-26 | Mitsubishi Heavy Ind Ltd | 排煙処理液浄化システム |
CN101078358A (zh) * | 2007-06-28 | 2007-11-28 | 韩培洲 | 具有脱硝流程的中冷等压吸热空气轮机 |
JP4719228B2 (ja) * | 2008-01-21 | 2011-07-06 | 三菱重工業株式会社 | 石炭焚ボイラの排ガス処理システム |
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JPS5517019A (en) * | 1978-07-19 | 1980-02-06 | Kobe Steel Ltd | Dry denitration method |
JPS5955234U (ja) * | 1983-08-01 | 1984-04-11 | バブコツク日立株式会社 | 燃焼装置 |
JPH08258980A (ja) * | 1995-03-27 | 1996-10-08 | Nippon Steel Corp | ホッパ内粉粒体の搬送状況判定方法および装置 |
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