JP2005265394A6 - Mixed fire boiler - Google Patents

Abstract

An object of the present invention is to provide a mixed combustion type boiler capable of burning a plurality of types of fuel with the same burner without providing a dedicated burner for each fuel type.
In a mixed-fired boiler that burns a plurality of types of fuel, a nozzle that blows fuel and oxygen-containing gas separately into a tubular combustion chamber in a tangential direction or a nozzle that blows a premixed gas of fuel and oxygen-containing gas is provided. A plurality of burners 11a to 11d that are provided so that a swirling flow is formed in the combustion chamber to generate a tubular flame are provided in the boiler furnace 10 and connected to the plurality of burners 11a to 11d. A plurality of burners 11a to 11d having a plurality of types of fuel pipes 13 to 16 so that one type of fuel selected from the plurality of types of fuel can be supplied to the plurality of burners 11a to 11d; A plurality of types of fuel pipes 13 to 16 are formed so as to be switchable.
[Selection] Figure 1

Description

  The present invention relates to a co-fired boiler that burns a plurality of types of fuel.

  In steelworks, combustible gases are generated from blast furnaces, coke ovens, converters, and the like, and these multiple types of by-product gases are all consumed in-house. This by-product gas is supplied as fuel in various manufacturing processes, and the remainder is supplied to the boiler of the power generation facility. For this reason, mixed-fired boilers that burn multiple types of fuel are installed at steelworks.

In the conventional mixed-fired boiler, as disclosed in Patent Document 1, a dedicated burner group is provided for each type of gas to be burned. This is because, for example, it is difficult to stably burn a plurality of gases having different gas components and greatly different calorific values with the same burner as in the case of burning blast furnace gas and coke oven gas.
JP-A-6-221516

  In conventional mixed-fired boilers, a dedicated burner group must be provided for each type of gas to be burned, which increases equipment costs and maintenance costs such as maintenance costs. That is, when it is possible to burn four types of gas, for example, a boiler having four burner groups for each fuel type requires 16 burners.

  The present invention has been made to solve the above-described problems, and provides a mixed combustion boiler that can burn a plurality of types of fuel with the same burner without providing a dedicated burner for each fuel type. With the goal.

  In order to solve the above-mentioned problem, the mixed-combustion boiler according to the first aspect of the present invention is a mixed-fired boiler that burns a plurality of types of fuel. In the mixed combustion boiler, the fuel and oxygen are directed tangentially to a tubular combustion chamber. There are provided a plurality of burners provided with nozzles for separately blowing the contained gas or nozzles for blowing a premixed mixture of fuel and oxygen-containing gas, and a swirling flow is formed in the combustion chamber to generate a tubular flame. A plurality of types of fuel pipes installed in a boiler furnace and connected to the plurality of burners, and one type of fuel selected from the plurality of types of fuel can be supplied to the plurality of burners As described above, the connection between the plurality of burners and the plurality of types of fuel pipes is formed to be switchable.

  A mixed-combustion boiler according to the invention of claim 2 is a mixed-fired boiler that burns a plurality of types of fuel, and a nozzle or fuel that separately blows fuel and an oxygen-containing gas into a tubular combustion chamber in a tangential direction. And a plurality of burners configured to generate a swirling flow in the combustion chamber to generate a tubular flame, and provided with a boiler furnace, A plurality of types of fuel pipes connected to a plurality of burners, and supplying one type of fuel selected from the plurality of types of fuel to the plurality of types of burners, or two types selected from the plurality of types of fuel The connection between the plurality of burners and the plurality of types of fuel pipes is formed to be switchable so that any one of the above-mentioned fuels can be selected from the supply to the specified number of burners. As Yes.

  A mixed-combustion boiler according to a third aspect of the present invention is a mixed-fired boiler that burns a plurality of types of fuel, and is a nozzle or fuel that separately blows fuel and oxygen-containing gas into a tubular combustion chamber in a tangential direction. And a plurality of burners configured to generate a swirling flow in the combustion chamber to generate a tubular flame, and provided with a boiler furnace, A plurality of types of fuel pipes connected to a plurality of burners, and supplying one type of fuel selected from the plurality of types of fuel to the plurality of types of burners, or two types selected from the plurality of types of fuel It is possible to select between supplying the above fuels to a specified number of burners or mixing two or more kinds of fuels selected from the plurality of types of fuels and supplying them to a plurality of burners. like, The connection between the plurality of burners and the plurality of types of fuel pipes is formed to be switchable.

  In the following description, a burner configured to generate the tubular flame is abbreviated as a tubular flame burner.

  In the present invention, since a special burner called a tubular flame burner is provided, one or more kinds selected from a plurality of kinds of fuels can be selected by the same burner group without providing a dedicated burner for each fuel type. The fuel can be burned.

The tubular flame burner provided in the boiler furnace of the present invention has the same basic structure as that described in Japanese Patent Laid-Open No. 11-281015, and refers to a burner having a structure as shown in FIG. This burner blows fuel and oxygen-containing gas into a tubular combustion chamber at a high speed to form a high-speed swirl, and ignites and burns this swirl flow. Since it is very wide, it is possible to burn even gases with greatly different calorific values. For example, it is possible to burn a low calorific value gas of about 600 Kcal / m ^3, which has a calorific value lower than that of the blast furnace gas, and to burn a high calorific value gas such as LNG. For this reason, in this invention, several types of fuel can be burned with the same burner group.

  And in the tubular flame burner, the fuel burns while swirling at a high speed, and a stable tubular flame that does not fluctuate can be formed. Stable combustion that does not allow for a low temperature region or a high temperature region. For this reason, the production | generation of soot and the production | generation of nitrogen oxide (NOx) are suppressed significantly. Furthermore, unlike a case where a diffusion flame is generated from a normal burner, a tubular flame that rotates at high speed is formed, so that the combustion is completed in a short time. For this reason, the generation of nitrogen oxides is further suppressed, and even if soot is generated, the time for soot particles to grow is not given, so the amount of generated soot is suppressed to a very small amount.

  By the way, a power generation boiler at a steel works is a facility where a large amount of exhaust gas is generated along with a steelmaking process equipped with a blast furnace, etc., and the gas composition of the exhaust gas has a great influence on the environmental load. According to this, since harmful components in the combustion exhaust gas can be suppressed to a very low level, the environmental load of the steelworks is reduced.

  According to the present invention, since a plurality of types of fuel can be burned by the same burner without providing a dedicated burner for each fuel type, the number of burner installations is reduced, and the equipment cost and the cost required for maintenance management are reduced. Is reduced.

  Moreover, since harmful components discharged from the boiler that generates a large amount of exhaust gas can be suppressed to a very low level, the environmental load is reduced.

  The present invention will be specifically described with reference to the drawings. FIG. 1 is a diagram showing a first example of an embodiment according to the configuration of the mixed combustion boiler of the present invention, FIG. 2 is a diagram showing a second example of the embodiment according to the configuration of the mixed combustion boiler of the present invention, and FIG. These are figures which show the 3rd example of embodiment which concerns on the structure of the mixed combustion boiler of this invention. And FIG. 4 is a figure which shows the basic composition of the tubular flame burner with which the mixed-fired boiler of this invention is equipped, and FIGS. 5-7 is a figure which shows the structure which concerns on the improved tubular flame burner.

  First, the basic structure of the tubular flame burner provided in each of the above embodiments will be described with reference to FIG. (A) A figure is a side view which notched a part, (b) A figure is sectional drawing of the AA arrow in (a) figure. Reference numeral 30 denotes a tubular combustion chamber, one end of which is opened to serve as a combustion gas discharge port. A long slit is formed in the other end portion of the combustion chamber 30 along the tube axis direction. The fuel blowing nozzle and the oxygen-containing gas blowing nozzle or the fuel and the oxygen-containing gas are connected to the slit. A nozzle 31 for blowing premixed gas is provided. The nozzle 31 is provided so that the blowing direction is substantially tangential to the inner wall surface of the combustion chamber, and a swirling flow is formed in the combustion chamber 30 by blowing the fuel or oxygen-containing gas. . A high-speed swirling flow can be formed in the combustion chamber by forming the shape of the tip of the nozzle 31 flat and reducing the opening area. Reference numeral 32 denotes a spark plug, and 100 denotes a tubular flame.

  Although FIG. 4 shows a case where a plurality of nozzles 31 are provided, the number of nozzles does not necessarily have to be plural, and only one nozzle may be provided. Further, in the above description, it is described that the gas outlet provided in the connection portion between the combustion chamber 30 and the nozzle 31 is a slit. However, in the present invention, the gas outlet is not limited to the slit. Absent. The gas outlet of the combustion chamber may be formed by a plurality of holes drilled adjacent to each other as long as it can form a high-speed swirling flow in the combustion chamber 30.

  In the burner configured as described above, when the air-fuel mixture that is blown from the nozzle 31 and forms a swirling flow is ignited, the gas in the combustion chamber 30 is stratified by the density difference, and the density differs on both sides of the flame. A gas layer is formed. That is, high-temperature combustion gas exists on the shaft center side where the turning speed is low, and unburned gas exists on the inner wall side where the turning speed is high.

  Further, in the vicinity of the inner wall, the swirling speed exceeds the flame propagation speed, and the flame does not propagate to the vicinity of the inner wall, so that the flame is generated in the combustion chamber 30 in a tubular shape. Further, since unburned gas exists near the inner wall of the combustion chamber, the wall surface of the combustion chamber 30 is not directly heated and exposed to high temperature. The gas in the combustion chamber 30 flows to the downstream side while swirling, and the gas on the inner wall side sequentially burns and moves to the axial center side and is discharged from the open end.

  The tubular flame burner configured as described above has many advantages. Among them, the advantages related to the present invention are as follows. Even if the fuel and the oxygen-containing gas are blown at a high speed, the center portion in the combustion chamber 30 has a low turning speed, so that a stable flame is always formed. For this reason, in the combustion region of each flame, combustion without causing a difference in fuel concentration and temperature is performed, and no local low temperature region is formed, so that no soot is generated.

  Also, since the fuel and oxygen-containing gas are blown at a high speed to form a swirling flow, the mixing property of the fuel and the oxygen-containing gas is good, and an extremely low calorific value that cannot be burned alone with a normal burner. The non-oxidizing atmosphere gas can be burned alone without separately supplying fuel.

  As described above, the tubular flame burner shown in FIG. 4 has the above-described advantages. A configuration in which this burner is further improved will be described.

  FIG. 5 is a view showing a first example of a configuration related to an improved tubular flame burner. FIG. 5A is a configuration diagram of the improved tubular flame burner, and FIG. 5B is a view taken along the line AA of FIG. In FIG. 5, parts having the same configuration as in FIG. In this tubular flame burner, an outer cylinder 40 is provided outside the combustion chamber 30 so that gas can flow between the combustion chamber 30 and the outer cylinder 40. Both the front end and the rear end of the outer cylinder 40 are closed ends, and the gas introduced from the pipe 42 connected to the front end side of the outer cylinder 40 is discharged from the pipe 43 connected to the rear end side. It has become. The oxygen-containing gas or fuel introduced from the pipe 42 and passing through the gas passage 41 between the combustion chamber 30 and the outer cylinder 40 and discharged from the pipe 43 is supplied to the blowing nozzle 31. .

  In the burner configured as described above, the oxygen-containing gas or fuel passes through the passage 41 and is preheated in contact with the outer surface of the high-temperature combustion chamber before being introduced into the nozzle 31. For this reason, the burnability of the burner is improved, and even a gas with a low calorific value can be burned.

  By the way, as described above, in the tubular flame burner, the gas in the combustion chamber 30 is stratified by the density difference, the high-temperature combustion gas is present on the axis side where the swirl speed is small, and the inner wall side where the swirl speed is large. Since unburned gas will be present in the combustion chamber 30, the inner wall of the combustion chamber 30 will not be exposed to high temperatures unless the flame length is shorter than the length of the combustion chamber 30.

  However, for example, when the amount of combustion is reduced, the length of the flame may be shorter than the length of the combustion chamber 30. Even when the amount of combustion is large, the length of the combustion chamber 30 must be longer than the length of the flame generated when the maximum load is burned due to the structure of the furnace to which the burner is attached. is there.

  In such a case, since there is no unburned low temperature gas layer near the inner wall, the temperature of the combustion chamber wall that has been maintained at a relatively low temperature rises. At this time, if the tip of the combustion chamber 30 is not formed of a heat resistant material, the tip may be damaged. However, if the combustion chamber 30 of the tubular flame burner has a double-cylindrical structure as shown in FIG. 5, the oxygen-containing gas and / or the fuel gas is preheated, so that the burnability of the burner is improved. Thus, even a gas with a low calorific value can be combusted. Further, since the combustion chamber 30 is cooled together with the preheating of the oxygen-containing gas and / or the fuel gas, the combustion chamber 30 is not damaged and the life of the burner is extended.

  FIG. 6 is a longitudinal sectional view showing a second example of the configuration related to the improved tubular flame burner. In FIG. 6, parts having the same configuration as in FIG. In this tubular flame burner, the combustion chamber 30 is composed of an inner cylinder 45 whose one end is opened and an outer cylinder 46 which is slidably attached along the outer peripheral surface of the inner cylinder 45. The outer cylinder 46 is a portion between the connection portion (nozzle injection port) of the nozzle for blowing the fuel and oxygen-containing gas in the inner cylinder 45 and the open end where the exhaust gas is discharged, and is along the outer peripheral surface of the inner cylinder 45. It is possible to adjust the length of the combustion chamber 30 to be longer or shorter by sliding the outer cylinder 46 in either direction. The lengths of the inner cylinder 45 and the outer cylinder 46 can be theoretically determined, but may be determined by repeating experiments. In the figure, 31a is a fuel injection nozzle, 31b is an oxygen-containing gas injection nozzle, and 32 is a spark plug. 100 indicates a tubular flame.

  If the combustion chamber 30 is configured as described above, the length of the combustion chamber 30 can be adjusted according to the length of the flame to be generated when the combustion amount is changed by sliding the outer cylinder 46.

  FIG. 7 is a view showing a third example of the configuration related to the improved tubular flame burner. In FIG. 7, the description of the portions related to the same configuration as in FIG. In FIG. 7, reference numeral 30 denotes a tubular combustion chamber, the tip 30a of which is opened to serve as an exhaust port for combustion exhaust gas. In the vicinity of the rear end 30b of the combustion chamber, there are a fuel injection nozzle 50 for injecting fuel gas and an oxygen-containing gas injection nozzle 51 for injecting oxygen-containing gas, the nozzle injection opening of which is opened on the inner surface of the combustion chamber 30. It is attached. These nozzles are provided with respect to the combustion chamber 30 so that the injection direction of the nozzles substantially coincides with the tangential direction of the circumferential surface of the combustion chamber, and swirl into the combustion chamber 30 by blowing oxygen-containing gas and fuel. Is to be formed. A high-speed swirling flow can be formed in the combustion chamber by forming the shape of the tip portion of the nozzle flat and reducing the opening area. A spark plug (not shown) may be attached in the vicinity of the rear end 30b of the combustion chamber.

  In the tubular flame burner 1 having the above-described configuration, the nozzle injection port is located on the inner surface of the combustion chamber 30 on the downstream side in the gas flow direction from the position where the fuel blowing nozzle 50 and the oxygen-containing gas blowing nozzle 51 are provided. An oxygen-containing gas blowing nozzle 52 for secondary combustion that is open at the bottom is provided. The oxygen-containing gas blowing nozzle 52 for secondary combustion is provided so that the injection direction of the nozzle substantially coincides with the tangential direction of the peripheral surface of the combustion chamber.

  Thus, the oxygen-containing gas blowing nozzle 52 for secondary combustion is provided downstream of the position where the fuel blowing nozzle 50 and the oxygen-containing gas blowing nozzle 51 are provided in the gas flow direction. By blowing the gas so that the injection direction of the gas substantially coincides with the tangential direction of the peripheral surface of the combustion chamber, two-stage combustion is performed in the combustion chamber 30 and the generation of NOx is suppressed.

  When the two-stage combustion is performed in the combustion chamber 30, the following effects are brought about. Even in the case of a tubular flame burner in which the generation of NOx is significantly suppressed, in order to further suppress the generation of NOx, particularly when burning a high calorific value fuel such as coke oven gas, Although it is necessary to further increase the flow velocity of the fuel and oxygen-containing gas blown into the fuel cell, it is not necessary to further increase the flow velocity of the blow-in by performing the two-stage combustion. For this reason, since it is not necessary to raise the specification pressure of the blower for blowing each gas, an installation cost and a running cost are reduced.

  Hereinafter, embodiments according to the configuration of the mixed-fired boiler of the present invention shown in FIGS. 1 to 3 will be sequentially described.

  The mixed-fired boiler according to the present invention includes a tubular flame burner. The basic structure of the tubular flame burner is as shown in FIG. And if necessary, the tubular flame burner by the structure shown in FIG. 5, the tubular flame burner by the structure shown in FIG. 6, or the tubular flame burner by the structure shown in FIG. 7 can be provided.

  A first example of the embodiment will be described with reference to FIG. FIG. 1 is a diagram showing a piping system of a co-fired boiler that burns multiple types of fuel. In addition, description of the combustion air piping is abbreviate | omitted. In FIG. 1, 10 is a boiler furnace, 11 is a tubular flame burner provided in the boiler furnace, and 12 is a heavy oil burner for supplying and burning heavy oil in an emergency. In this boiler, a plurality of burners 11 are provided, and a plurality of types of fuel pipes are connected. 13 is a blast furnace gas (B gas) pipe, 14 is a coke oven gas (C gas) pipe, 15 is a converter gas (LD gas) pipe, and 16 is a city gas pipe. By switching the connection of the fuel pipes, one type of fuel selected from a plurality of types of fuel can be supplied to a plurality of burners.

For example, when one type of B gas is supplied from the above four types of fuel, the valve a ₁ is opened, and the valves c ₁ to c ₃ and the valves f ₁ to f ₄ are opened. B gas can be supplied to the four burners 11a to 11d. When one kind of C gas is supplied, the valve a ₂ is opened, and the valves c ₁ to c ₃ and the valves f ₁ to f ₄ are opened.

  The flow rate of the fuel supplied to each burner 11a to 11d is controlled based on the amount of steam generated by a combustion control device (not shown).

  A second example of the embodiment will be described with reference to FIG. FIG. 2 is a diagram showing another example of a piping system of a mixed combustion boiler that burns a plurality of types of fuel. In FIG. 2, the parts already described in FIG. This boiler can supply one type of fuel selected from a plurality of types of fuel to a plurality of burners by switching the connection of fuel pipes, and also supply two or more types of fuels to the specified number of burners. It is possible to supply. For this reason, it is possible to select a plurality of fuel types in accordance with the supply status of each fuel type and to burn the fuel types in combination.

For example, when supplying B gas and C gas to each of two burners, if the valves a ₁ , d ₁ , and e ₁ are opened and the valves f ₁ and f ₂ are opened, 2 B gases are supplied. Can be supplied to the base burners 11a and 11b, and then the valves a ₂ , c ₂ , d ₃ and e ₃ are opened, and the valves f ₃ and f ₄ are opened. Two burners 11c and 11d can be supplied.

  A third example of the embodiment will be described with reference to FIG. FIG. 3 is a view showing still another example of a piping system of a mixed combustion boiler that burns a plurality of types of fuel. This boiler supplies one type of fuel selected from a plurality of types of fuel to a plurality of burners by switching the connection of fuel pipes, and supplies two or more types of fuel to the specified number of burners. In addition, two or more kinds of fuels can be mixed and supplied to a plurality of burners. For this reason, as in the case of FIG. 2, it is possible to select a plurality of fuel types according to the supply status of each fuel type, and to combine the fuel types for combustion, and to mix and generate a calorific value. Regulated fuel can be supplied to each burner.

  In FIG. 3, the parts already described in FIG. In FIG. 3, reference numeral 20 denotes a fuel mixer, and reference numerals 21a to 21d denote flow rate adjusting devices that adjust the flow rates of the respective fuels based on instruction signals sent from a combustion control device (not shown).

In this boiler, when two or more kinds of fuels are mixed and burned, for example, in order to mix and burn B gas and C gas, the valves a ₁ and g ₁ are opened, and the valves a ₂ and g are opened. after the ₂ to open, if the valve h ₁ ~ valve h ₄ in the open, B gas and C gas are mixed in a predetermined ratio, it is supplied to the burner 11a~11d of four.

  In FIGS. 1 to 3, the number of burners installed is four, and the types of fuel to be supplied are B gas, C gas, LD gas, and city gas. In the present invention, the number of burners installed and the type of fuel are not limited to those shown in FIGS.

As described above, in the present invention, since the tubular flame burner capable of stably burning a wide variety of fuel types is provided, it is necessary to provide a dedicated burner for each fuel type as in a conventional mixed-fired boiler. Rather, a single burner can burn a variety of fuel types.
For this reason, the number of burners installed in the boiler furnace can be greatly reduced, and a significant reduction in equipment costs and maintenance costs can be achieved.

  In addition, in a tubular flame burner that burns while swirling at a high speed, a local low-temperature region or high-temperature region cannot be formed, so that generation of soot and harmful components such as nitrogen oxides (NOx) are greatly suppressed. For this reason, an environmental load is reduced.

It is a figure which shows the 1st example of embodiment which concerns on the structure of the mixed combustion boiler of this invention. It is a figure which shows the 2nd example of embodiment which concerns on the structure of the mixed combustion boiler of this invention. It is a figure which shows the 3rd example of embodiment which concerns on the structure of the mixed combustion boiler of this invention. It is a figure which shows the basic composition of the tubular flame burner with which the mixed combustion boiler of this invention is equipped. It is a figure which shows the 1st example of the structure which concerns on the improved tubular flame burner. It is a figure which shows the 2nd example of the structure which concerns on the improved tubular flame burner. It is a figure which shows the 3rd example of the structure which concerns on the improved tubular flame burner.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Boiler furnace 11a, 11b, 11c, 11d Tubular flame burner 13 B gas piping 14 C gas piping 15 LD gas piping 16 City gas piping 20 Fuel mixer 21a, 21b, 21c, 21d Flow control device 30 Combustion chamber 31 Injection nozzle 32 Spark plug 50 Fuel injection nozzle 51 Oxygen-containing gas injection nozzle 52 Oxygen-containing gas injection nozzle for secondary combustion

Claims (3)

  In a mixed combustion type boiler for burning a plurality of types of fuel, a nozzle for separately blowing a fuel and an oxygen-containing gas in a tangential direction into a tubular combustion chamber or a nozzle for blowing a premixed gas of a fuel and an oxygen-containing gas is provided, A plurality of burners configured so that a swirling flow is formed in the combustion chamber to generate a tubular flame, the boiler furnace is provided with a plurality of types of fuel pipes connected to the plurality of burners, The connection between the plurality of burners and the plurality of types of fuel pipes is switchable so that one type of fuel selected from the plurality of types of fuel can be supplied to the plurality of burners. This is a mixed-fired boiler.   In a mixed combustion type boiler for burning a plurality of types of fuel, a nozzle for separately blowing a fuel and an oxygen-containing gas in a tangential direction into a tubular combustion chamber or a nozzle for blowing a premixed gas of a fuel and an oxygen-containing gas is provided, A plurality of burners configured so that a swirling flow is formed in the combustion chamber to generate a tubular flame, the boiler furnace is provided with a plurality of types of fuel pipes connected to the plurality of burners, Supplying one type of fuel selected from the plurality of types of fuel to the plurality of burners, or supplying two or more types of fuel selected from the plurality of types of fuel to the specified number of burners, respectively. A mixed-fired boiler characterized in that the connection between the plurality of burners and the plurality of types of fuel pipes is switchable so that either one can be selected.   In a mixed combustion type boiler for burning a plurality of types of fuel, a nozzle for separately blowing a fuel and an oxygen-containing gas in a tangential direction into a tubular combustion chamber or a nozzle for blowing a premixed gas of a fuel and an oxygen-containing gas is provided, A plurality of burners configured so that a swirling flow is formed in the combustion chamber to generate a tubular flame, the boiler furnace is provided with a plurality of types of fuel pipes connected to the plurality of burners, Supplying one type of fuel selected from the plurality of types of fuel to the plurality of burners, or supplying two or more types of fuel selected from the plurality of types of fuel to the specified number of burners, or Two or more types of fuel selected from a plurality of types of fuel are mixed and supplied to the plurality of burners, so that it is possible to select any one of the plurality of burners and the plurality of types of fuel pipes. Contact A mixed-fired boiler characterized in that the connection is formed to be switchable.

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