JP2012112569A - Combustion method to prevent contamination of combustion chamber of petroleum residue fired boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustion method to prevent contamination of a combustion chamber of a petroleum residue fired boiler, capable of preventing degradation of heat exchanging performance and contamination of the combustion chamber due to attachment of melted combustion ash including vanadium oxide to a water pipe of the combustion chamber, when deteriorated fuel such as petroleum residue of high content of vanadium is used as a fuel.SOLUTION: In the combustion chamber 1 including a high-temperature reduction combustion zone 2 having a throttle section 4 at its outlet, and a low-temperature oxidation combustion zone 3 having a cooling section 9 in a region from the throttle section 4 of the high-temperature reduction combustion zone to a position of an air supply nozzle 7 for two-stage combustion, an average gas temperature in the high-temperature reduction combustion zone 2 is within a range of 1,450-1,550°C, and the air for two-stage combustion is supplied when an exhaust gas temperature of the reduction combustion zone is cooled to 1,200-1,350°C at the cooling section 9 to perform the combustion in an oxidation atmosphere, thus a ratio of a component of low-melting point in the vanadium oxide is reduced.

Description

  The present invention relates to a combustion method for preventing vanadium attack and preventing fouling of a combustion chamber in a boiler using petroleum-based residue containing vanadium such as oil coke as fuel.

  For example, inferior fuels such as asphalt and oil coke may be used as boiler fuel from the viewpoint of saving petroleum resources and saving fuel costs. However, since petroleum-based residues such as oil coke have a high vanadium content, ash containing a low melting point pentavalent vanadium oxide is produced when the petroleum residue is oxidized and burned as fuel in a normal boiler. Vanadium oxide melts at a high temperature in the boiler combustion chamber and becomes soot and adheres to the heat transfer surface, lowering the heat transfer coefficient, reducing the heat recovery of the boiler, and destroying the oxide film on the metal surface. Accelerated high-temperature oxidation (vanadium attack) corrodes metals, making continuous boiler operation difficult.

  As a method to prevent vanadium oxide from adhering to the heat transfer surface, a magnesium-based additive is mixed into the fuel to increase the melting point of the combustion ash, making it difficult to melt at the temperature of the combustion chamber, making the ash on the surface of the water tube There are techniques to reduce adhesion. However, this method not only increases the amount of combustion ash, but also has the harmful effect of increasing the amount of NOx generated.

Further, in Patent Document 1, when a crude heavy oil containing vanadium or the like is used in a marine boiler, the ash of the low melting point vanadium compound melts and adheres to the outer surface of the heat exchanger as a flea. In order to be able to withstand thinning against so-called vanadium attack that corrodes metal by accelerated high-temperature oxidation, a method is disclosed in which a protective member that is less affected by vanadium attack is applied to the heat transfer tube portion to which vanadium-containing combustion ash adheres. .
In the method described in Patent Document 1, not only is the protective member expensive, but a plurality of plate-shaped protective members that cover the heat transfer tubes are provided for each heat transfer tube, so that the construction cost is high.

The applicant has already developed a low NOx boiler having a high temperature reduction combustion zone and a low temperature oxidation combustion zone, which can use inferior fuels such as asphalt and oil coke as boiler fuel. Patent Document 2 discloses an inverted low-NOx boiler that has been disclosed by the applicant, and in particular, enables continuous operation for a long period of time by continuously discharging the combustion ash accumulated in the furnace bottom.
The low NOx boiler disclosed in Patent Document 2 forms a high temperature reduction combustion zone for burning fuel in a reducing atmosphere at the most upstream part of the combustion chamber, and an inner peripheral wall downstream thereof via a throttle part of the combustion gas flow path. The water-cooled wall structure is used, and a low-temperature oxidation combustion zone is formed in which a two-stage combustion air nozzle is attached to the side wall.

In the high temperature reduction combustion zone, the fuel is burned while maintaining an average high temperature of about 1450 to 1550 ° C. in the state of fuel richness, and the combustion gas that has entered the low temperature oxidation combustion zone through the constricted portion is used as a two-stage combustion air nozzle From this, combustion air is newly supplied to complete combustion in a relatively low-temperature oxidizing atmosphere at 1100 ° C. below the low-temperature oxidation combustion zone.
The amount of NOx generated in the combustion of petroleum residues, etc., decreases as the temperature increases in the reducing atmosphere and decreases as the temperature decreases in the oxidizing atmosphere. Therefore, petroleum residues are burned in two stages: high temperature reduction combustion and low temperature oxidation combustion. By doing so, the amount of NOx generation can be effectively reduced.

  Vanadium reduced combustion ash has a melting point of 1600 ° C. or higher, but even in reducing combustion, if it is kept at a high temperature of 1400 ° C. or higher for a long time, or if it is kept at 1200 ° C. or higher for a long time in an oxidizing combustion atmosphere, the vanadium oxide becomes pentavalent. The vanadium combustion ash becomes a low melting point ash having a melting point of 700 ° C. or lower and activates the vanadium attack.

JP 2009-198117 A JP 2010-139176 A

  The present invention, when using inferior fuel such as petroleum residue having a large vanadium content that causes vanadium attack as a fuel, combustion ash containing vanadium oxide dissolves and adheres to the combustion chamber water pipe and heat exchange characteristics It is an object of the present invention to provide a combustion chamber contamination-preventing combustion method for an oil residue-fired boiler that does not deteriorate the quality or contaminate the combustion chamber.

  In order to solve the above-mentioned problems, a combustion chamber contamination preventing combustion method for a petroleum residue-fired boiler according to the present invention includes a high-temperature reduction combustion zone having a throttle at the outlet, and blowing of air for two-stage combustion from the throttle of the high-temperature reduction combustion zone In a combustion chamber having a low temperature oxidation combustion zone in which a cooling part is formed in a region up to the nozzle position, the average gas temperature in the high temperature reduction combustion zone is in the range of 1450 to 1550 ° C., and the reduction combustion zone exhaust gas temperature in the cooling part Is cooled to 1200 to 1350 ° C., and air for two-stage combustion is blown and burned in an oxidizing atmosphere. Note that the cooling unit can realize the cooling described above by adjusting the amount and flow rate of the water flow, the amount and flow rate of the hot gas, and the like.

The vanadium combustion ash produced in the high temperature reduction combustion zone in the oxygen-poor atmosphere at a temperature of 1450 to 1550 ° C includes divalent vanadium oxide (VO) having a melting point of 1790 ° C and trivalent vanadium oxide (V) having a melting point of 1970 ° C. ₂ O ₃ ), tetravalent vanadium oxide (V ₂ O ₄ ) having a melting point of 1640 ° C., and many others having a high melting point, including pentavalent vanadium oxide (V ₂ O ₅ ) having a melting point as low as 690 ° C. The amount is small.
In addition, by cooling the gas temperature to 1200 to 1350 ° C before blowing in the air for two-stage combustion and suppressing the formation of pentavalent vanadium oxide, complete combustion is ensured to ensure thermal efficiency. can do.

  Under such combustion conditions, the vanadium oxide, which is mostly composed of high melting point vanadium oxide, does not melt in the combustion chamber composed of the high-temperature reduction combustion zone and the low-temperature oxidation combustion zone, and maintains the powder. It does not fuse to the surface of the water pipe and the combustion chamber is not contaminated. Therefore, it is possible to continue a stable operation while maintaining the amount of heat collected in the combustion chamber.

The low NOx boiler is more preferably an inverted type.
In an inverted low-NOx boiler, fuel is burned in a high-temperature reducing atmosphere at the upper end of the combustion chamber, spouted from the throttle and cooled in the cooling unit, and then generated while the two-stage combustion air is mixed and completely burned The vanadium combustion ash does not melt and maintains the powder, does not contaminate the heat transfer surface, and deposits on the bottom of the combustion chamber. Since the vanadium combustion ash deposited on the bottom can be discharged from the opening at the bottom while the boiler is in operation, the boiler can be operated continuously for a long time.

  The combustion method for preventing combustion chamber contamination of a petroleum residue fired boiler according to the present invention is a vanadium attack in which vanadium combustion ash dissolves and adheres to a combustion chamber water pipe and corrodes metal when petroleum residue having a high vanadium content is used as fuel. By suppressing the above, boiler operation can be continued while maintaining high thermal efficiency.

1 is a schematic functional diagram of an inverted low NOx boiler according to a first example of one embodiment of the present invention. FIG. It is a schematic perspective perspective view of the inverted low NOx boiler of this embodiment. It is a graph which shows melting | fusing point of vanadium oxide. It is a graph which illustrates notionally the change of the combustion gas temperature in the combustion chamber of the inverted low NOx boiler of this embodiment. It is a graph explaining the relationship between fuel burnout and ash adhesion amount.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings with different drawing numbers, the same reference numerals are assigned to the same components to facilitate understanding.

(First embodiment)
FIG. 1 is a schematic functional diagram of a low NOx boiler according to a first example of the present embodiment, and FIG. 2 is a schematic perspective perspective view thereof. In this embodiment, an inverted low NOx boiler is targeted. FIG. 3 is a graph showing the melting point of vanadium oxide, FIG. 4 is a graph for conceptually explaining changes in the combustion gas temperature in the combustion chamber, and FIG. 5 is a graph for explaining the relationship between fuel burnout and ash adhesion amount. is there.

The inverted low NOx boiler in the present embodiment is formed with a high temperature reduction combustion zone 2 at the upper end of a vertical combustion chamber 1 and a low temperature oxidation combustion zone 3 at the lower stage, and the high temperature reduction combustion zone 2 and the low temperature oxidation combustion zone. 3 is connected by the throttle part 4 of the high temperature reduction combustion zone 2. The throttle unit 4 preferably has an opening ratio that reduces the horizontal cross-sectional area of the combustion chamber by 20 to 50%.
The high temperature reduction combustion zone 2 is provided with a burner 5 on the side wall, and the inner wall is covered with a refractory material 6 corresponding to the furnace temperature of 1450 ° C. to 1550 ° C. It is preferable that the burner 5 installed in the high temperature reduction combustion zone 2 is arranged such that a plurality of burners 5 are horizontally parallel to the two opposing side surfaces and the flame axes do not intersect.

In the low temperature oxidation combustion zone 3, a cooling unit 9, a two-stage combustion unit 10, and an ash discharge unit 8 are formed.
The cooling unit 9 includes a region shown by oblique hatching divided by level A and level B in FIG. 1, that is, a throttle unit 4 serving as an entrance of the low-temperature oxidation combustion zone 3 and a two-stage combustion air nozzle 7 provided on the side wall. The combustion gas in the range of 1450 ° C. to 1550 ° C. formed between the high temperature reduction combustion zone 2 and supplied via the throttle 4 is cooled to the range of 1200 ° C. to 1350 ° C.
The cooling unit 9 is designed based on the shape of the cooling unit and the water pipe on the side wall, based on the heat exchange efficiency of the cooling surface, the area of the cooling surface, the temperature, amount and flow velocity of the water flow, the temperature, amount and flow velocity of the hot gas, etc. Thus, the cooling is realized by adjusting the temperature drop amount of the combustion gas.

The two-stage combustion air nozzle 7 is arranged on the furnace wall at the upper end portion of the two-stage combustion section 10 and in contact with the lowermost portion of the cooling section 9, and supplies fresh air to the cooled combustion gas so that it remains unburned. Is burned in two stages in a low-temperature oxidizing atmosphere. The two-stage combustion unit 10 has a water-cooled wall structure in which a water pipe is arranged on a side wall, and generates steam from the water in the water pipe by heat exchange.
The water pipe is connected to a non-heated downcomer (not shown) at the bottom of the combustion chamber 1, and a sufficiently high pressure is applied to the high-temperature reduction combustion zone 1 through a nonheated downcomer from a brackish water cylinder (not shown) provided at a position higher than the combustion chamber 1. The cooling water can be supplied.

At the bottom of the low temperature oxidation combustion zone 3, an ash discharge part 8 is formed. The ash discharge unit 8 is formed by forming the furnace bottom of the combustion chamber with an inclined surface of 45 ° or less, preferably about 35 ° with respect to the vertical line, and an ash discharge mechanism disposed at the lower end of the inclined surface. It is possible to efficiently discharge the combustion ash collected in the outside of the furnace with a simple structure.
A gas outlet 11 is provided on the lower surface of the two-stage combustion section 10 and communicates with the gas passage 12. The gas passage 12 conveys the combustion gas to the post-processing step after passing through the steam superheater tube 13 and the economizer 14. An ash discharge port 15 is also provided at the bottom of the gas passage in which the steam superheater tube 13 and the economizer 14 are disposed.

The inverted low NOx boiler of this embodiment is a thermal power boiler that recovers thermal energy from combustion gas by burning liquid, gaseous, and finely powdered fuel, and suppresses the amount of NOx contained in the combustion gas. it can. Further, since the inverted low NOx boiler of this embodiment can easily process the combustion ash, inferior fuels such as asphalt and oil coke can also be used as boiler fuel.
The inverted low NOx boiler of the present embodiment supplies fuel and air to the upper end portion of the combustion chamber 1 and burns it in a high temperature reducing atmosphere, and advances the combustion downward from the upper end portion. Thus, the combustion of unburned gas is completed in a lower temperature oxidizing atmosphere, and the combustion gas is taken out from the lower part.

When using an inferior fuel such as petroleum residue in the inverted low NOx boiler of this embodiment, first, fuel and air are introduced into the burner 5 in the high temperature reduction combustion zone 2 to start combustion. In the high-temperature reduction combustion zone 2, the introduction of air is suppressed, the air ratio is maintained at a reducing atmosphere of 1 or less, for example, about 0.6 to 0.8, and selected from 1450 ° C. to 1550 ° C. depending on the fuel. Burn the fuel at a high temperature in the range.
In the high-temperature reduction combustion zone 2, the combustion gas vortexes in the horizontal direction and convects due to the flame from the burner 5 arranged with the axis shifted horizontally. Further, in combination with the low temperature of the high temperature reduction combustion zone 2 and the low density of the combustion gas, the combustion gas stays in the high temperature reduction combustion zone 2 for a long time, and is kept warm by the refractory material 6 so that the combustion spreads stably. .

The combustion gas that has become high temperature in the combustion in the high temperature reduction combustion zone 2 is pushed out from the high temperature reduction combustion zone 2 through the throttle portion 4 because the combustion gas is increased by the newly introduced fuel, and the low temperature oxidation combustion zone 3. To flow down.
The combustion gas flowing down to the low temperature oxidation combustion zone 3 is cooled to a temperature in the range of 1200 ° C. to 1350 ° C. while passing through the cooling unit 9, and is supplied to the two-stage combustion unit 10.
In the two-stage combustion section 10, a relatively low-temperature two-stage combustion air is sufficiently supplied from the two-stage combustion air nozzle 7 so that the air ratio becomes about 1.1, and the unburned portion of the combustion gas is within the oxidizing atmosphere. It is completely burned.
The combustion gas that completes combustion in the two-stage combustion section 10 exchanges heat with the water pipe on the inner wall of the two-stage combustion section 10 and drops in temperature from about 1000 ° C. to about 1100 ° C. The gas flow provided on the lower side surface of the combustion chamber The gas flows out from the outlet 11 to the gas passage 12. In the gas passage 12, the steam superheater pipe 13 and the economizer 14 exchange heat with boiler steam and feed water, and then flow out to the post-treatment process.

Thus, in the inverted low NOx boiler of this embodiment, the fuel is initially burned in the high temperature reducing atmosphere in the high temperature reducing combustion zone 2 and further burned in two stages in the low temperature oxidizing combustion zone 3 in the low temperature oxidizing atmosphere.
The amount of NOx generated when fuel such as petroleum residue burns strongly depends on the combustion temperature and the air ratio. The lower the air ratio, that is, the lower the amount of NOx generated, the lower the temperature in the reducing atmosphere, and the lower the temperature in the oxidizing atmosphere, the lower the amount of NOx generated.
In the inverted low NOx boiler of the present embodiment, this characteristic is used to suppress the generation of NOx by reacting with the intermediate product in the high temperature reducing atmosphere of the high temperature reducing combustion zone 2 and being reduced to nitrogen. In the low-temperature oxidative combustion zone 3, when the gas temperature falls, the second stage combustion air is introduced to completely burn the unburned portion, thereby suppressing the generation of thermal NOx, effectively reducing the amount of NOx generated can do.

When using inferior fuel such as oil coke as boiler fuel, attention must be paid to vanadium metal contained in the fuel. The low melting point vanadium oxide generated when oxidizing and burning petroleum residues melts at the high temperature in the boiler combustion chamber and adheres to the heat transfer surface, lowering the heat transfer coefficient, and accelerating high temperature oxidation (vanadium attack) Corrosion.
In the inverted low NOx boiler of the present embodiment, vanadium contained in the fuel burns in a reducing atmosphere in the high temperature reduction combustion zone 2, so that the generated vanadium combustion ash is valence 5 pentoxide 2 vanadium (V ₂ The content of O ₅ ) is small, and a large amount of vanadium oxide having a valence of 4 or less is contained.

FIG. 3 is a graph showing the melting point of vanadium oxide. As shown in FIG. 3, the melting point of pentavalent vanadium oxide (V ₂ O ₅ ) having a high degree of oxidation is relatively low at 690 ° C., whereas the melting point of divalent vanadium oxide (VO) is 1790. The melting point of trivalent vanadium oxide (V ₂ O ₃ ) is 1970 ° C., and the melting point of tetravalent vanadium oxide (V ₂ O ₄ ) is as high as 1640 ° C.
Therefore, in the high temperature reduction combustion zone 2 from 1450 ° C. to 1550 ° C., the vanadium combustion ash does not melt and maintains the solid phase, so that it is sufficient to adhere to the heat transfer surface and deteriorate the heat transfer efficiency or corrode the metal. It is suppressed.

  Further, the vanadium combustion ash generated in the high temperature reduction combustion zone 2 falls into the low temperature oxidation combustion zone 3 along with the combustion gas or falls due to its own weight. Vanadium combustion ash containing a large amount of components having a small valence and a high melting point enters the low-temperature oxidation combustion zone 3 and is first cooled to a temperature in the range of 1200 ° C. to 1350 ° C. The part 10 is burned at a low temperature in an oxidizing atmosphere.

In the low temperature oxidative combustion zone 3, oxygen is in an excessive environment. Therefore, when high temperature combustion is performed, vanadium oxide having a small valence is further oxidized, and the pentavalent vanadium oxide (V ₂ O) having a melting point as low as 690 ° C. is easily melted. ₅ ) However, since the two-stage combustion section 10 burns at a relatively low temperature, the oxidation reaction for changing vanadium oxide having a small valence to pentavalent vanadium oxide is not active. Thus, by rapidly cooling the combustion gas, an increase in pentavalent vanadium oxide can be suppressed and adhesion to the heat transfer tube can be suppressed.
Therefore, in the low temperature oxidation combustion zone 3, the melting of vanadium combustion ash is small, and most of it settles as ash and deposits in the ash discharge part 8 at the bottom of the combustion chamber 1.

  FIG. 4 is a graph conceptually illustrating changes in the combustion gas temperature in the combustion chamber of the inverted low NOx boiler of the present embodiment. The graph of FIG. 4 shows the temperature change of the combustion gas when moving from the reduction combustion zone to the oxidation combustion zone with the horizontal axis representing the movement path of the combustion gas in the combustion chamber and the vertical axis representing the combustion gas temperature. is there. In the graph, the vertical line drawn at the boundary between the reduction combustion zone and the oxidation combustion zone indicates the position of the throttle portion, and the arrow indicates the position of the air nozzle for two-stage combustion that inputs the secondary air.

A diagram represented by a solid line shows a design line for changes in combustion gas temperature when the combustion chamber contamination prevention combustion method of the oil residue-fired boiler of this embodiment is used.
Combustion gas burns in the high temperature reduction combustion zone where the air ratio λ becomes about 0.7, reaches a temperature of 1450 ° C. to 1550 ° C., flows down to the low temperature oxidation combustion zone through the throttle, and is cooled in the cooling unit. In the region A where the gas temperature is about 1200 ° C. to 1350 ° C., newly cooled secondary air is supplied from the two-stage combustion air nozzle, and low temperature oxidation combustion with an air ratio of about 1.1 is performed. At the exit of the combustion chamber, the gas temperature is from 1000 ° C to 1100 ° C.
In addition, since melting | fusing point of vanadium combustion ash produced | generated in a reduction | restoration combustion zone is 1640 degreeC or more and is higher than a reduction | restoration combustion temperature, the powder is maintained.

The design line in the figure is designed for the purpose of satisfying ultra-low NOx / low dust performance in an inverted low NOx boiler, and further reducing the amount of ash adhesion by reducing the unburned content in the combustion chamber. The gas temperature before the secondary air is blown in the low-temperature oxidation combustion zone is preferably about 1200 to 1350 ° C. expressed as the region A.
On the other hand, when the temperature is set to 1200 ° C. or lower represented as the region B in FIG. 4, a large amount of unburned portion is inconvenient. When the temperature is set to 1350 ° C. or higher represented as the region C, the ash adhesion amount Is inconvenient.

FIG. 5 is a graph illustrating the relationship between fuel burnout and ash adhesion. In the graph, the horizontal axis represents burnout and the amount of ash adhesion on an arbitrary scale, and the vertical axis represents the gas temperature in oxidation combustion.
Vanadium combustion ash (vanadium reduced ash) generated by reductive combustion partially changes to pentavalent vanadium oxide (V ₂ O ₅ ) having a low melting point by oxidative combustion.
When the gas temperature is lowered, the production rate of pentavalent vanadium oxide is slowed, and the amount of ash deposited by fusion of vanadium oxide is reduced. However, if the combustion temperature in the boiler is lowered, the burning out becomes worse and a large amount of unburned matter is generated, so that the efficiency of the boiler is lowered.
For example, as shown as region B in FIGS. 4 and 5, when the combustion gas is rapidly cooled in the cooling section so that it becomes 1200 ° C. or lower and around 800 ° C. at the secondary air charging position, unburned in the combustion gas As the amount of time increases, it is not suitable as an operating condition.

Conversely, as shown in region C, the gas temperature at the secondary air input position is a high temperature of about 1350 ° C. or more and about 1400 ° C. without particularly actively cooling in the cooling unit from the throttle unit to the two-stage combustion air nozzle. , The burn-out performance is improved and the unburned content is reduced, but since the production of pentavalent vanadium oxide becomes active, the amount of ash adhesion increases and the vanadium attack is received. Not suitable as a condition.
On the other hand, in the case of the present embodiment, the combustion gas having a temperature of 1450 ° C. to 1550 ° C. is cooled by the cooling unit and is represented by a region A from 1200 ° C. to 1350 ° C. at the position of the two-stage combustion air nozzle. Thus, the relationship between burn-out and ash adhesion amount is balanced, the combustion gas contains less unburned matter, the combustion ash contains less pentavalent vanadium oxide, and the combustion chamber is extremely less contaminated. .

  About 60 to 70% of the combustion ash composition of oil coke is vanadium oxide, but even if nickel or silicon oxide is mixed in as the other main component, it is quickly gasified in the combustion chamber of the low NOx boiler of this embodiment. Since the melting is suppressed by cooling, the amount of combustion ash adhering to the surface of the water tube is extremely small.

Since the ash discharge part 8 has a steep inclined surface, the solid combustion ash falling toward the furnace bottom gathers at the bottom of the ash discharge part 8, and the combustion ash deposited on the bottom is discharged by the ash discharge mechanism. can do. The ash discharge mechanism may be configured to always open, or may be provided with a lid-like bottom plate so that it can be opened and closed, and when necessary, the bottom plate may be opened to discharge and collect ash.
The residual ash entrained in the combustion gas is separated from the gas and dropped when the combustion gas becomes low speed in the gas passage 12 where the steam superheater pipe 13 and the economizer 14 are provided, and the gas passage provided in the gas passage 12. It is collected at the ash discharge port 15 for use.

  Further, since the combustion gas circulating in the vicinity of the ash discharge part 8 is completely burned in the two-stage combustion part 10, there are few harmful substances such as carbon monoxide and sulfide generated by incomplete combustion, and the toxicity is low. In addition, since the ash discharge mechanism is outside the two-stage combustion unit 10, even if air flows from the opening, there is little risk of inhibition of combustion due to cooling and a reduction in the denitration effect due to collapse of the air ratio.

In this embodiment, since the ash discharge unit 8 is provided in the boiler, the ash can be discharged safely even while the furnace is in operation. Therefore, long-term continuous operation that cannot be achieved with a conventional low NOx boiler is possible. And maintenance costs are reduced. Moreover, since inferior fuel containing many ash content, such as C heavy oil, asphalt, oil coke, etc., can be used, fuel cost can be reduced.
In addition, even when vanadium metal is included in the fuel, a kind of vanadium combustion ash that is difficult to melt is generated, so that it prevents fusion to the heat exchange surface, maintains heat exchange efficiency, and prevents vanadium attack. Corrosion of metals such as water pipes can be suppressed.

  Combustion chamber dirt prevention combustion method of petroleum residue fired boiler of the present invention is a vanadium that dissolves vanadium combustion ash and adheres to the combustion chamber water pipe and corrodes metal when using petroleum residue with high vanadium content as boiler fuel. By suppressing the attack, the boiler operation can be continued while maintaining high thermal efficiency.

DESCRIPTION OF SYMBOLS 1 Combustion chamber 2 High temperature reduction combustion zone 3 Low temperature oxidation combustion zone 4 Constriction part 5 Burner 6 Refractory material 7 Two-stage combustion air nozzle 8 Ash discharge part 9 Cooling part 10 Two-stage combustion part 11 Gas outlet 12 Gas passage 13 Steam overheating Tube 14 Economizer 15 Ash outlet

Claims (4)

  In a combustion chamber comprising a high-temperature reduction combustion zone having a throttle at the outlet, and a low-temperature oxidation combustion zone in which a cooling part is formed in a region from the throttle of the high-temperature reduction combustion zone to the position of the air blowing nozzle for two-stage combustion The average gas temperature in the high-temperature reduction combustion zone is set to a range of 1450 to 1550 ° C., the high-temperature reduction combustion zone exhaust gas temperature is cooled to 1200 to 1350 ° C. in the cooling section, and then the two-stage combustion air is blown into the oxidizing atmosphere. A combustion method for preventing contamination of a combustion chamber of a petroleum residue-fired boiler, characterized in that the combustion is performed in a combustion chamber.   A combustion chamber comprising a high-temperature reduction combustion zone having a throttle at the outlet, and a low-temperature oxidation combustion zone in which a cooling part is formed in a region from the throttle of the high-temperature reduction combustion zone to the position of the air blowing nozzle for two-stage combustion A combustion chamber of a petroleum residue-fired boiler, wherein the cooling section is configured to cool the reduced combustion zone exhaust gas having an average gas temperature in the range of 1450 to 1550 ° C to 1200 to 1350 ° C.   The combustion chamber of an oil residue-fired boiler according to claim 2, wherein the constricted part of the high-temperature reduction combustion zone reduces the horizontal cross-sectional area of the combustion chamber by 20 to 50%.   The oil residue-fired boiler includes a combustion chamber having an upper end of the high-temperature reduction combustion zone, a low-temperature oxidation combustion zone below the high-temperature reduction combustion zone, and a discharge unit that discharges combustion ash at the lower end of the low-temperature oxidation combustion zone. The combustion chamber of a petroleum residue-fired boiler according to claim 2 or 3, which is an inverted low NOx boiler.

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