JP6255923B2 - Combustion device, gas turbine, and power generation device - Google Patents

Description

  The present invention relates to a combustion apparatus, a gas turbine, and a power generation apparatus.

  There are various NOx reduction techniques in combustion, and broadly divided into two types: one that reduces NOx in the combustor and one that reduces NOx outside the combustor. As an example of the former, there are those that reduce the combustion temperature by lowering the fuel concentration, those that inject steam into the combustor to reduce the combustion temperature, and those that use a catalyst. Examples of the latter include an ammonia catalytic reduction method, a non-catalytic reduction method, and an oxidation reduction method. For example, Patent Document 1 below describes a gas turbine combustor that injects water vapor into the combustor to reduce the combustion temperature, while Patent Document 2 described below discloses NOx ( A technique for reducing (nitrogen oxide) using a catalyst in the presence of ammonia gas is described.

JP 09-119638 A Special table 2010-519025 gazette

  By the way, since the technique which reduces NOx outside a combustor requires the apparatus which reduces NOx besides a combustor, there exists a possibility of causing the cost increase of a combustion apparatus. Therefore, considering the cost aspect, it is preferable to reduce NOx in the combustor.

  However, even in the technology for reducing NOx in the combustor, the technology for injecting water vapor into the combustor requires a device for supplying water vapor to the combustor, so combustion is performed in the same manner as the technology for reducing NOx outside the combustor. There is a risk of increasing the cost of the apparatus. In addition, the technology for reducing the fuel concentration is advantageous in terms of cost, but generally the flame holding performance of the flame is lowered. Therefore, in an application in which power is generated using a combustion device such as an engine, for example, the output range of the power There is a problem that is limited. Further, in the technology using a catalyst, since a rare metal such as platinum or palladium is used as a catalyst, there is a problem that the catalyst is expensive and maintenance is complicated and expensive because periodic catalyst replacement is necessary.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a NOx reduction technique that is simpler than before.

  In order to achieve the above object, according to the present invention, as a first solving means related to a combustion apparatus, a combustion apparatus that performs multistage combustion in a combustor, wherein at least ammonia is used as a fuel for final stage combustion combustion. And means for supplying an ammonia supply device to the combustion chamber and an other fuel supply device for supplying a predetermined fuel to the combustor for a stage other than the stage in which the ammonia supply apparatus supplies ammonia.

  In the present invention, as the second solving means relating to the combustion apparatus, in the first solving means, the multistage combustion is a two-stage combustion, and the other fuel supply apparatus is configured to use a predetermined fuel for the first-stage combustion. Is supplied to the combustor, and the ammonia supply device employs means for supplying ammonia to the combustor as fuel for second stage combustion.

  In the present invention, as a third solving means relating to the combustion apparatus, in the second solving means, the combustor is a first-stage combustion region (first-stage combustion region) on the upstream side of the internal space, and downstream of the combustor. A means is adopted in which the side is an area for second stage combustion (second stage combustion area).

  In the present invention, as a fourth solving means related to the combustion apparatus, in the third solving means, a means is provided in which the throttle portion is formed in the internal space between the ammonia supply stage and the ammonia supply stage. Is adopted.

  In the present invention, as a fifth solving means related to the combustion apparatus, in any one of the first to fourth solving means, a premixing unit that premixes fuel and air for the first stage combustion is provided. Adopt the means.

  In the present invention, as the first solving means related to the gas turbine, a means is provided which includes the combustion apparatus according to any one of the first to fifth solving means.

  In the present invention, as a second solving means related to the gas turbine, a combustion apparatus according to the first solving means comprising a first combustor for first stage combustion and a second combustor for second stage combustion; Means comprising a first turbine driven by the exhaust gas of the first combustor and a second turbine driven by the exhaust gas of the second combustor, wherein the exhaust gas of the first turbine is supplied to the second combustor. Is adopted.

  In the present invention, means for driving the generator with the gas turbine according to the first or second solution means is adopted as the solution means for the power generator.

  According to the present invention, it is only necessary to generate high-temperature exhaust gas in the first stage combustion, and to burn ammonia in the second stage combustion using the heat of the high-temperature exhaust gas. Is possible.

It is a block diagram which shows the structure of the electric power generating apparatus which concerns on 1st Embodiment of this invention. It is a characteristic view which shows the NOx reduction effect of the combustion apparatus which concerns on 1st Embodiment of this invention. In 1st Embodiment of this invention, it is the 1st schematic diagram which shows the supply form of ammonia to a combustor. In 1st Embodiment of this invention, it is the 2nd schematic diagram which shows the supply form of ammonia to a combustor. It is a block diagram which shows the structure of the electric power generating apparatus which concerns on 2nd Embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
[First Embodiment]
First, the first embodiment will be described. The power generator according to the first embodiment includes a gas turbine 1 and a generator 2 as shown in FIG. That is, this power generator is of a type that drives the generator 2 with the power of the gas turbine 1. The gas turbine 1 is an internal combustion engine that generates rotational power by high-pressure exhaust gas obtained by burning fuel as is well known, and drives a generator 2. The generator 2 is driven by the gas turbine 1 to output predetermined AC power (for example, three-phase AC power) to the outside.

  The gas turbine 1 includes a compressor (compressor) 1a, a premixing unit 1b, a combustion chamber 1c, a turbine 1d, a natural gas supply device 1e, and an ammonia supply device 1f (another fuel supply device). Of these components, the premixing portion 1b and the combustion chamber 1c constitute the combustor C in the present embodiment, and the compressor 1a, the combustor C, the natural gas supply device 1e, and the ammonia supply device 1f are The combustion apparatus (reference number omitted) in the present embodiment is configured.

  The compressor 1a is an axial-flow type rotary compressor in which a rotating shaft is axially coupled to an output shaft of the turbine 1d. The compressor 1a compresses air taken in from the atmosphere by being driven to rotate by the turbine 1d to be supplied to the premixing unit 1b. Supply. That is, the compressor 1a generates compressed air having a predetermined pressure to be used for fuel combustion in the combustor C and supplies the compressed air to the premixing unit 1b. Note that the compression ratio of air in the compressor 1 a is appropriately set according to the specifications of the combustor C.

  The combustor C includes a premixing portion 1b in the front stage of the combustion chamber 1c. The premixing unit 1b is a functional unit that mixes the compressed air supplied from the compressor 1a with the natural gas supplied from the natural gas supply device 1e, and is a lean premixed gas (diluted) obtained by the mixing. (Premixed gas) is supplied to the combustion chamber 1c. This lean premixed gas has an air-fuel ratio (a dimensionless number obtained by dividing the air mass by the fuel mass) greater than the stoichiometric air-fuel ratio (the air-fuel ratio when oxygen and fuel in the mixed gas react without excess or deficiency), That is, the fuel is in a thin state (lean state) with respect to oxygen.

  The combustion chamber 1c corresponds to a two-stage combustion method (also referred to as a reheating method), and an internal space (combustion space) has a first-stage combustion region R1 and a second-stage combustion region R2. The first stage combustion region R1 is located upstream in the flow direction of the lean premixed gas supplied from the premixing section 1b, and burns the lean premixed gas supplied from the premixing section 1b (first stage combustion). Let On the other hand, the second stage combustion region R2 is adjacent to the first stage combustion region R1 on the downstream side in the flow direction of the lean premixed gas, and burns ammonia supplied as fuel from the ammonia supply device 1f (second Stage combustion).

  That is, in the first stage combustion region R1, the natural gas in the lean premixed gas burns using oxygen contained in the lean premixed gas as an oxidant (first stage combustion), and in the second stage combustion region R2. Then, ammonia burns (second stage combustion) using residual oxygen in the high-temperature exhaust gas generated in the first stage combustion as an oxidant. The high-temperature and high-pressure exhaust gas generated by the second stage combustion is supplied from the combustion chamber 1c to the turbine 1d.

  Here, ammonia is generally known as a substance that burns but has low flammability (difficult to burn). However, in the second stage combustion, a high temperature atmosphere (high temperature exhaust gas generated in the first stage combustion ( For example, ammonia can be stably combusted (oxidized) by 600 ° C. or higher. Ammonia is also known as a substance having a reducing action.

  The turbine 1d is an axial-flow turbine that rotates using high-temperature and high-pressure exhaust gas supplied from the combustion chamber 1b as a driving fluid. The output shaft of the turbine 1d is axially coupled to the rotating shaft of the compressor 1a as described above, and is also axially coupled to the rotating shaft of the generator 2. The turbine 1d generates rotational power by high-temperature and high-pressure exhaust gas to drive the generator 2. The high-temperature and high-pressure exhaust gas is exhausted from the turbine 1d as exhaust gas with reduced pressure and temperature by recovering power by the turbine 1d. The exhaust gas discharged from the turbine 1d is discharged into the atmosphere after being subjected to exhaust gas treatment as necessary.

  The natural gas supply device 1e is a device that supplies natural gas having a predetermined flow rate to the premixing unit 1b as combustion. The ammonia supply device 1f is a device that supplies ammonia at a predetermined flow rate to the combustion chamber 1c as combustion. The flow rate of natural gas in the natural gas supply device 1e and the flow rate of ammonia in the ammonia supply device 1f are appropriately controlled by a control device (not shown).

  Next, the operation of the power generation apparatus configured as described above, particularly the operation of the gas turbine 1, will be described in detail with reference to FIG.

  In the gas turbine 1 according to the present embodiment, the compressed air generated by the compressor 1a is mixed with natural gas in the premixing section 1b of the combustor C to generate a lean premixed gas. The lean premixed gas is supplied from the premixing portion 1b to the first stage combustion region R1 of the combustion chamber 1c, and is ignited in the first stage combustion region R1 to perform the first stage combustion.

  Since the lean premixed gas is generated in the premixing section 1b as a lean premixed gas, the high-temperature exhaust gas obtained by the first stage combustion contains residual oxygen. This high-temperature exhaust gas containing residual oxygen is quickly supplied from the first-stage combustion region R1 to the adjacent second-stage combustion region R2, and second-stage combustion is performed using ammonia as fuel.

  The high-temperature exhaust gas generated by the first stage combustion is a high-temperature gas containing residual oxygen and having a necessary and sufficient temperature (for example, 600 ° C. or higher) to stably burn ammonia. In other words, in the first stage combustion, the combustion conditions are set so as to obtain a temperature necessary and sufficient for stably burning ammonia in the second stage combustion. In this way, although generally combusted, ammonia known as a flame retardant substance can be reliably combusted in the second stage combustion region R2.

  Since the exhaust gas generated by the second stage combustion is obtained by compressed air, the first stage combustion, and the second stage combustion, it is a high-temperature and high-pressure gas, and has sufficient kinetic energy to drive the turbine 1d. have. The high-temperature and high-pressure exhaust gas obtained by the second stage combustion is supplied as a driving fluid from the combustion chamber 1c to the turbine 1d to drive the turbine 1d. That is, the turbine 1d is driven by the high-temperature and high-pressure exhaust gas supplied from the combustion chamber 1c, and thereby powers the generator 2 that is shaft-coupled. As a result, the generator 2 outputs power to the outside.

  Here, FIG. 2 is a characteristic diagram (simulation result) showing the NOx reduction effect of the combustion apparatus in the first embodiment. That is, this characteristic diagram shows the relationship between the combustion temperature in the second stage combustion (second stage temperature: horizontal axis) and the NOx reduction rate (vertical axis). The NOx reduction rate on the vertical axis is obtained by subtracting the NOx concentration contained in the high-temperature exhaust gas after the first stage combustion from the NOx concentration contained in the high-temperature exhaust gas after the second stage combustion from the NOx concentration. It is a value divided by the NOx concentration contained in the high temperature exhaust gas after combustion. The simulation conditions (calculation conditions) set for obtaining this simulation result are as follows.

〔Calculation condition〕
(1) First stage combustion simulated exhaust gas (oxygen concentration (dry): 16.3%, NOx (converted to 16% O ₂ ): 479 ppm)
(2) Residence time: 10msec
(3) Pressure: 20 atmospheres (4) Ammonia (NH ₃ ) input: Doubled by volume with respect to NOx (5) Calculation method: PSR (Perfectly Stirred Reactor) model with simulated exhaust gas and NH 3 gas mixture as inlet gas Calculation.
(6) Reaction mechanism: Carbonization based on “Naik, CV, W. Pitz, et al. (2005)“ Detailed Chemical Kinetic Modeling of Surrogate Fuels for Gasoline and Application to an HCCI Engine ”SAE 2005-01-3741” A detailed reaction mechanism for the reaction between hydrogen and nitrogen oxides.
(7) The reactor temperature was constant, and the temperature range of the second stage combustion was 600 ° C to 1400 ° C.

  As shown in FIG. 2, ammonia not only functions as a fuel in the second stage combustion, but also has a function of reducing NOx (nitrogen oxide) in the high-temperature exhaust gas generated by the first stage combustion. That is, according to the characteristic diagram of FIG. 2, when the combustion temperature (second stage temperature) in the second stage combustion is relatively low, the NOx reduction rate is a positive value, that is, the high temperature exhaust gas generated in the first stage combustion. However, when the second stage temperature is relatively high, that is, when it is higher than 1300 ° C., it is lower than the non-value, that is, the NOx quantity of the high-temperature exhaust gas generated in the first stage combustion. Value. For example, when the second stage temperature is 1400 ° C., a NOx reduction rate exceeding 30% can be obtained.

  According to this characteristic diagram, the NOx amount of the high-temperature exhaust gas generated in the first stage combustion can be reduced by setting the flow rate of ammonia so that the combustion temperature in the second stage combustion becomes higher than 1300 ° C. . That is, the temperature of the high-temperature exhaust gas obtained by the first stage combustion is sufficiently high, and it is sufficiently possible to raise the combustion temperature in the second stage combustion to more than 1300 ° C. by adjusting the flow rate of ammonia. Therefore, the NOx amount of the high temperature exhaust gas generated in the first stage combustion can be sufficiently reduced.

  For example, in the first embodiment, by setting the flow rate of ammonia supplied from the ammonia supply device 1f to the second stage combustion region R2 of the combustion chamber 1c so that the combustion temperature in the second stage combustion becomes 1350 ° C., about − A NOx reduction rate of 10% is obtained. Therefore, according to the first embodiment, since it is only necessary to burn ammonia in the combustor C of the gas turbine 1, NOx can be reduced extremely simply. Note that the NOx reduction effect due to the combustion of ammonia is due to the reduction action that ammonia inherently has.

In addition, this invention is not limited to the said 1st Embodiment, For example, the following modifications can be considered.
(1) In the first embodiment, the combustor C having the first stage combustion region R1 and the second stage combustion region R2 is provided in the combustion chamber 1c. However, the present invention is limited to this. Not. A combustor that includes a combustion chamber (first combustion chamber) for the first stage combustion region R1 and a combustion chamber (first combustion chamber) for the second stage combustion region R2 may be employed.

(2) Moreover, as a supply form of ammonia to the combustion chamber 1c in the first embodiment, for example, the one shown in FIGS. 3A and 3B can be considered. In the configuration shown in FIG. 3A, a plurality of nozzles N for injecting ammonia are directed to the center of the combustion chamber 1c and inclined to the downstream side at a substantially intermediate position in the flow direction of the lean premixed gas (the right method in the drawing). Thus, ammonia is injected toward the second stage combustion region R2.

  The configuration shown in FIG. 3 (b) is the same as the configuration shown in FIG. 3 (a), in which the throttle portion S, that is, the flow path area is locally between the first stage combustion region R1 and the second stage combustion region R2. A combustion chamber 1g provided with a narrowly set portion is provided. According to this form, the flow rate of the high temperature exhaust gas generated in the first stage combustion can be made faster than that in the form of FIG. 3A, so that the high temperature exhaust gas and ammonia (fuel) in the second stage combustion region R2 Mixing can be further promoted.

(3) In the first embodiment, the lean premixed gas is generated in the premixing unit 1b, but the present invention is not limited to this. In the premixing unit 1b, a premixed gas (fuel rich concentrated premixed gas) in which the fuel is richer than oxygen (rich state) may be generated. However, in this case, in order to secure oxygen for the second stage combustion, it is necessary to mix diluted air with ammonia and inject it into the second stage combustion region R2 from each nozzle N as shown in FIG. There is. In this case, ammonia and diluted air may be injected into the second stage combustion region R2 by a dedicated nozzle provided separately.

  Further, when supplying the fuel rich premixed gas for the turn flow type combustor, an opening H is formed on the peripheral surface of the inner chamber T2 provided in the outer chamber T1, as shown in FIG. 4B. At the same time, a partition plate P is provided around the opening H, the tip of each nozzle N is opened in the partition plate P, and ammonia is supplied to each nozzle N. By adopting such a configuration, it is possible to inject diluted air, not dense air, together with ammonia into the second stage combustion region R2 through each nozzle N and each opening H.

[Second Embodiment]
Next, a second embodiment will be described with reference to FIGS. In these drawings, the same reference numerals are given to the same components as those of the first embodiment.

  As shown in FIG. 5, the power generator according to the second embodiment includes a gas turbine 1A, a generator 2, a waste heat recovery boiler 3 (second combustor), an ammonia supply device 1f, a second turbine 4, and a second generator. 5 is provided. The gas turbine 1A includes a compressor (compressor) 1a, a premixing unit 1b, a combustion chamber 1h, a turbine 1d (first turbine), and a natural gas supply device 1e. In the second embodiment, a combustor C1 (first combustor) is configured by the premixing unit 1b and the combustion chamber 1h. Furthermore, in this embodiment, the combustion apparatus is comprised by the combustor C1 (1st combustor), the natural gas supply apparatus 1e, the waste heat recovery boiler 3, and the ammonia supply apparatus 1f.

  That is, the power generator according to the second embodiment drives the generator 2 with the power of the gas turbine 1A and drives the second generator 5 with the power of the second power device. The generator 2 is driven by the gas turbine 1A to output predetermined AC power (for example, three-phase AC power) to the outside, and the second generator 5 is driven by the second power unit to generate a predetermined AC. Electric power (for example, three-phase AC power) is output to the outside.

  The combustion chamber 1h has a single combustion space, ignites and burns the lean premixed gas supplied from the premixing section 1b, and supplies the high-temperature and high-pressure exhaust gas generated by the combustion to the turbine 1d. That is, the combustor C1 is a single chamber combustor having one combustion space. The turbine 1 d drives the generator 2 by taking in the high-temperature and high-pressure exhaust gas supplied from the combustion chamber 1 h as a driving fluid, and discharges the exhaust gas whose pressure and temperature have decreased to the waste heat recovery boiler 3.

  The waste heat recovery boiler 3 has both functions of a combustor and a heat exchanger. That is, the waste heat recovery boiler 3 generates heat by burning ammonia, which is a fuel, in the presence of exhaust gas supplied from the turbine 1d, and heats water supplied from the outside by the heat to increase the temperature. Generate high-pressure steam. The waste heat recovery boiler 3 supplies the high-temperature and high-pressure steam to the second turbine 4 as a driving fluid, and discharges (exhausts) the exhaust gas to the atmosphere after treating the exhaust gas.

  Here, the exhaust gas supplied from the turbine 1d to the waste heat recovery boiler 3 is lower in temperature than the high-temperature high-pressure exhaust gas supplied from the combustion chamber 1h to the turbine 1d by power recovery by the turbine 1d. The boiler 3 has a sufficient temperature (for example, 600 ° C. or higher) to stably burn ammonia. In other words, the combustion conditions in the combustion chamber 1h are set so that a temperature necessary and sufficient for stably burning ammonia in the waste heat recovery boiler 3 is obtained.

  The ammonia supply device 1 f supplies ammonia as a fuel to such a steam generator 3. The second turbine 4 is an axial-flow steam turbine that drives the second generator 5 by taking in the high-temperature and high-pressure steam supplied from the steam generator 3 as a driving fluid, and the exhaust gas whose pressure and temperature have decreased. To the outside.

  The power generator according to the first embodiment performs the first-stage combustion and the second-stage combustion in the gas turbine 1 by adopting the combustor C of the two-stage combustion method, but the power generator according to the second embodiment First stage combustion is performed in the combustion chamber 1h of the gas turbine 1A, and second stage combustion is performed in the steam generator 3 provided separately from the gas turbine 1A. That is, in the power generation apparatus according to the second embodiment, natural gas is combusted (first stage combustion) in the gas turbine 1A to generate power in the turbine 1d, and ammonia is combusted in the steam generator 3 (second stage). (Combustion) to generate power in the second turbine 4.

  According to such a power generator according to the second embodiment, although the temperature of the high-temperature high-pressure exhaust gas obtained in the combustion chamber 1h is decreased by the turbine 1d, the flow rate of ammonia supplied to the waste heat recovery boiler 3 is adjusted. Thus, it is possible to set the combustion temperature in the waste heat recovery boiler 3 to be slightly higher than 1300 ° C., and thus NOx of exhaust gas obtained from the gas turbine 1A can be reduced.

In addition, this invention is not limited to the said 1st, 2nd embodiment, For example, the following modifications can be considered.
(1) In the first embodiment, the two-stage combustion type combustor C is adopted, and in the second embodiment, the two-stage combustion type combustor C1 (first combustor) and the waste heat recovery boiler 3 (second combustion). However, the present invention is not limited to such two-stage combustion. The combustor is configured to perform two or more stages of multi-stage combustion. At least ammonia is supplied as fuel for the final stage combustion, and a predetermined fuel such as natural gas is supplied to a stage other than the stage supplying the ammonia. May be.

  For example, when three-stage combustion is adopted, natural gas is burned in the first stage combustion, ammonia is burned in the second stage combustion and the third stage combustion, or natural gas is burned in the first stage combustion and the second stage combustion. It is conceivable that gas is burned and ammonia is burned in the third stage combustion which is the final stage combustion.

(2) In the first and second embodiments, the case where the combustion apparatus according to the present invention is applied to the gas turbine 1, 1A (internal combustion engine) has been described, but the present invention is not limited to this. The combustion apparatus according to the present invention may be applied to an internal combustion engine other than the gas turbines 1 and 1A.

(3) In the first and second embodiments, natural gas is used as the fuel for the first stage combustion, but the present invention is not limited to this. A fuel other than natural gas may be employed.

(4) In the first and second embodiments, the combustion temperature of the second stage combustion is set to a temperature at which NOx can be reduced by adjusting the supply amount of ammonia, but the present invention is not limited to this. The combustion temperature of the first stage combustion may be adjusted by adjusting the flow rate of the natural gas, and the combustion temperature of the second stage combustion may be set to a temperature at which NOx can be reduced by adjusting the supply amount of ammonia.

(5) In the first and second embodiments, an axial-flow rotary compressor is used as the compressor 1a. However, the present invention is not limited to this. For example, a centrifugal rotary compressor may be used.

  1, 1A gas turbine, 1a compressor, 1b premixing section, 1c, 1g, 1h combustion chamber, 1d turbine (first turbine), 1e natural gas supply device (other fuel supply device), 1f ammonia supply device, 2 power generation Machine, 3 waste heat recovery boiler (second combustor), 4 second turbine, 5 second generator, C combustor, C1 combustor (first combustor), R1 first stage combustion region, R2 second stage Combustion area

Claims (8)

A combustion device that performs multistage combustion in a combustor,
An ammonia supply device for supplying ammonia to the combustor as a fuel for at least the final stage combustion combustion;
Another fuel supply device for supplying a predetermined fuel to the combustor for a stage before the stage in which the ammonia supply apparatus supplies ammonia ;
Equipped with,
A combustion apparatus characterized in that the fuel is burned in a state where oxygen is larger than a stoichiometric air-fuel ratio . The multistage combustion is a two-stage combustion,
The other fuel supply device supplies a predetermined fuel to the combustor for the first stage combustion,
The combustion apparatus according to claim 1, wherein the ammonia supply apparatus supplies ammonia to the combustor as a fuel for second stage combustion.   The combustor is characterized in that the upstream side of the internal space is a first stage combustion region (first stage combustion region) and the downstream side is a second stage combustion region (second stage combustion region). The combustion apparatus according to claim 2.   4. The combustion apparatus according to claim 3, wherein a throttle portion is formed in the internal space between an ammonia supply stage and an ammonia supply stage.   The combustion apparatus according to claim 1, further comprising a premixing unit that premixes fuel and air for the first stage combustion.   A gas turbine comprising the combustion device according to any one of claims 1 to 5. The combustion apparatus according to claim 2, comprising a first combustor for the first stage combustion and a second combustor for the second stage combustion;
A first turbine driven by the exhaust gas of the first combustor;
A second turbine driven by waste heat of the second combustor,
The gas turbine, wherein the second combustor is supplied with exhaust gas from the first turbine.   A generator is driven by the gas turbine according to claim 6 or 7.

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