JP5821553B2 - RQL low NOx combustor - Google Patents

Description

  The present invention reduces the amount of NOx (nitrogen oxide) emissions, burns a mixture of fuel and air, and generates combustion gas. RQL (Rich burn Quick quench Lean burn) (Combustion) type low NOx combustor.

  In recent years, combustors used in gas turbines such as jet engines have been required to reduce NOx emissions from the viewpoint of environmental protection. In order to meet the demand, RQL low NOx having a simple configuration is required. Combustors have been developed. This low NOx combustor of the RQL method performs rich combustion (primary combustion) of a mixture of fuel and primary air in a fuel rich state (oxygen-deficient state) in a primary combustion region in a combustion chamber of a combustor liner, The flame temperature is obtained by performing lean combustion (secondary combustion) in the secondary combustion region in the combustion chamber of the combustor liner in an oxygen-excess state (fuel lean state) with a mixture of combustion gas and secondary air from the primary fuel region. This is a combustion system that lowers the NOx emission amount and reduces NOx emissions.

  In addition, there exist some which are shown to patent document 1-patent document 3 as a prior art relevant to this invention.

JP 2011-208938 A JP 2011-163626 A JP 2009-74798 A

  By the way, in order to reduce the amount of NOx emission during operation of the RQL type low NOx combustor by over-concentration combustion in the primary combustion region, a sufficient primary combustion region is secured in the combustion chamber, and mixing in the primary combustion region is performed. Qi homogeneity (mixing degree) needs to be improved. On the other hand, when the primary combustion region is enlarged in the combustion chamber, the secondary combustion region is reduced by that amount, and smoke (smoke) discharged by over-concentration combustion in the primary combustion region is sufficiently burned (lean). Combustion), and smoke emissions during operation of the low NOx combustor increase. That is, there is a problem that it is difficult to achieve both reduction of NOx emission amount and reduction of smoke emission amount during operation of the low NOx combustor.

  Accordingly, an object of the present invention is to provide an RQL-type low NOx combustor having a novel configuration that can solve the above-described problems.

  In order to solve the above-mentioned problems, the inventor of the present invention prototyped a plurality of test products simulating an RQL type low NOx combustor, the position of the secondary air introduction hole in the main flow direction, and the combustor liner. While changing the ratio of the flow rate of secondary air introduced from multiple secondary air introduction holes to the flow rate of all air introduced into the combustion chamber (secondary air flow rate ratio) as a parameter, multiple test products A combustion test was conducted. And as a result of conducting the combustion test, the inventor of the present invention sets the flow rate ratio of the secondary air to 20 to 70% even when each secondary air introduction hole is brought close to the fuel injection valve. New knowledge that NOx (nitrogen oxide), CO (carbon monoxide), and THC (unburned hydrocarbon) emissions during operation of a low NOx combustor can be reduced, and the present invention is completed. It came to do. Here, when each secondary air introduction hole is brought close to the fuel injection valve, the position in the main flow direction of each secondary air introduction hole is the average flow rate in the non-combustion state (the average flow rate during operation of the low NOx combustor). ) Is set to a position on the upstream side from the point where the flow (main flow) flowing in (1) reaches in 1/3 hour of the residence time in the combustion chamber.

An aspect of the present invention is used in a gas turbine, and is a low RQL method that generates a combustion gas by burning a mixture of fuel and air (primary air and secondary air) while reducing NOx emissions. In a NOx combustor, a combustor liner having a partition on the upstream side and having a combustion chamber for burning an air-fuel mixture inside, and fuel injection provided in the partition and injecting (spraying) fuel into the combustion chamber A primary air introduction member provided on the partition wall and introducing primary air into the combustion chamber, and a plurality of secondary airs that introduce secondary air into the combustion chamber on the peripheral surface of the combustor liner Air introduction holes are provided at intervals along the circumferential direction, and an air-fuel mixture of fuel and primary air is passed upstream of the secondary air introduction holes in the combustion chamber in a fuel rich state (oxygen-deficient state). Primary combustion for rich combustion (primary combustion) A region is formed, and a mixture of the combustion gas and the secondary air from the primary combustion region is lean-burned in an oxygen-excess state (fuel lean state) downstream of the secondary air introduction hole in the combustion chamber ( A secondary combustion region for secondary combustion) is formed, and the position of each secondary air introduction hole in the main flow direction is an average flow velocity in the non-combustion state (during operation of the low NOx combustor). The average flow velocity of the secondary air introduction holes is set at a location where the flow (main flow) flowing at a rate of 1/5 to 1/3 hours of the residence time in the combustion chamber is reached, The ratio of the flow rate of secondary air introduced from the plurality of secondary air introduction holes to the flow rate of all air introduced into the combustion chamber (secondary air flow rate ratio) is set to 20 to 70%. Ru der that it is.

  In the specification and claims of the present application, “provided” means not only directly provided but also indirectly provided via another member. The “main flow direction” refers to the flow direction of the main flow of air, air-fuel mixture or combustion gas, and “upstream side” refers to the upstream side when viewed from the main flow direction, and “downstream side”. Means the downstream side when viewed from the mainstream direction.

According to an aspect of the present invention, fuel is injected into the combustion chamber by the fuel injection valve, and primary air is introduced from the primary air introduction member into the combustion chamber, so that the fuel and the primary in the primary combustion region. An air-fuel mixture is burned with rich fuel in a fuel rich state to generate combustion gas. Subsequently, a large amount of secondary air is introduced into the combustion chamber from the plurality of secondary air introduction holes, so that the combustion gas and the secondary air rapidly move between the primary combustion region and the secondary combustion region. In the secondary combustion region, the air-fuel mixture of the combustion gas and the secondary air is lean-burned in an oxygen-excess state (fuel lean state), and combustion gas is generated and discharged from the combustor liner. Further, the turbine disposed on the downstream side of the low NOx combustor can be driven by continuously performing the rich combustion in the primary combustion region and the lean combustion in the secondary combustion region.

  Here, since the total opening area of the plurality of secondary air introduction holes is set so that the flow rate ratio of the secondary air is 20 to 70%, each secondary air introduction hole is used as the fuel injection valve. Specifically, the position of each secondary air introduction hole in the main flow direction is set to the upstream position from the predetermined location, so that NOx during operation of the low NOx combustor, CO and THC emissions can be reduced. In other words, while ensuring combustion stability in the primary combustion region, the secondary combustion region is reduced in the combustion chamber while reducing NOx, CO, and THC emissions during operation of the low NOx combustor. Can be secured sufficiently.

  According to the present invention, while ensuring combustion stability by the primary combustion region, the secondary NOx in the combustion chamber is reduced while reducing emissions of NOx, CO, and THC during operation of the low NOx combustor. Since a sufficient combustion area can be secured, smoke (smoke) discharged by over-rich combustion in the primary combustion area is sufficiently burned (lean combustion) in the secondary combustion area, and the low NOx combustor is operating. The amount of smoke discharged in can be reduced. Therefore, it is possible to achieve both the reduction of NOx, CO, and THC emissions during the operation of the low NOx combustor and the reduction of smoke emissions.

FIG. 1 is a partial side cross-sectional view of an RQL type low NOx combustor according to an embodiment of the present invention. FIG. 2 is a view taken along line II-II in FIG. FIG. 3 is a view taken along line III-III in FIG.

  An embodiment of the present invention will be described with reference to FIGS. 1 to 3. In the drawings, “F” indicates the forward direction (upstream side), and “R” indicates the backward direction (downstream side).

  As shown in FIG. 1 and FIG. 2, the low NOx combustor 1 of the RQL (Rich burn Quick quench Lean burn) system according to the embodiment of the present invention reduces the amount of NOx emission. In the meantime, an air-fuel mixture of fuel and air (primary air, secondary air) is burned to generate combustion gas. The low NOx combustor 1 is a so-called annular combustor that is often used in a jet engine (not shown).

  The low NOx combustor 1 includes a hollow annular combustor case 3, and the combustor case 3 has an annular outer case 5 and an engine center EC of a jet engine inside the outer case 5. And an annular inner case 7 provided concentrically. Further, air (compressed air) from a compressor (not shown) in the jet engine can be introduced to the inlet side of the combustor case 3.

  In the combustor case 3, a hollow annular combustor liner 9 is provided concentrically. The combustor liner 9 is provided with an annular outer liner 11 and an annular concentrically provided inside the outer liner 11. And an annular partition wall (front wall) 15 provided so as to connect the outer liner 11 and the inner liner 13 to the upstream side (front side). Further, the combustor case 3 has an annular combustion chamber 17 for combusting an air-fuel mixture of fuel and air (primary air, secondary air) on the inner side, in other words, the outer liner 11 and the inner liner. An annular combustion chamber 17 is defined between the two and 13. The outer liner 11, the inner liner 13, and the partition wall 15 are formed with a plurality of cooling holes (not shown) for performing film cooling and the like.

  The partition wall 15 is provided with a plurality of fuel injection valves (fuel injection nozzles) 19 that spray fuel as a conical spray flow S in the combustion chamber 17 at intervals along the circumferential direction. The valve 19 is a spiral injection valve having a known configuration, for example, and has an injection hole (nozzle hole) 19h capable of spraying fuel at the center (center portion). In addition, the outer case 5 is provided with a plurality of fuel supply pipes 21 that can supply fuel at intervals along the circumferential direction of the concentric circles, and the tip of each fuel supply pipe 21 has a corresponding fuel supply. It is connected to the base of the injection valve 19. A plurality of spark plugs (not shown) for igniting (igniting) fuel in the combustion chamber 17 are provided at appropriate positions on the outer case 5 so as to protrude toward the combustion chamber 17.

  Around each fuel injection valve 19 in the partition wall 15, a swirler (axial flow swirler or tangential flow swirler) 23 is provided as a primary air introduction member that introduces primary air into the combustion chamber 17 as a swirling flow. Further, the total opening area of the swirler 23 is such that the ratio of the flow rate of primary air introduced from the swirler 23 to the flow rate of all air introduced into the combustion chamber 17 (primary air flow rate ratio) is 20% or less. Is set to The primary air flow rate ratio is set to be 20% or less. If the primary air flow rate ratio exceeds 20%, it becomes difficult to sufficiently secure the secondary air flow rate ratio described later. This is because the NOx emission reduction effect is reduced.

  Outer sleeves 25 and outer sleeves 27 protrude from the outer peripheral surface 11 (outer peripheral surface of the combustor liner 9) toward the combustion chamber 17 and are alternately provided along the circumferential direction. An outer secondary air introduction hole 25h for introducing secondary air into the combustion chamber 17 is provided on the inner side, and each outer sleeve 27 has an outer secondary for introducing the secondary air into the combustion chamber 17 on the inner side. A secondary air introduction hole 27h is provided. In other words, the outer secondary air introduction hole 25 h and the outer secondary air introduction hole 27 h are alternately provided on the peripheral surface of the outer liner 11 along the circumferential direction via the plurality of outer sleeves 25 and 27. Similarly, on the peripheral surface of the inner liner 13 (inner peripheral surface of the combustor liner 9), an inner sleeve 29 and an inner sleeve 31 protrude toward the combustion chamber 17 side and are provided alternately along the circumferential direction. The sleeve 29 has an inner secondary air introduction hole 29 h for introducing secondary air into the combustion chamber 17 on the inner side, and each inner sleeve 31 has the secondary air inside the combustion chamber 17 on the inner side. An inner secondary air introduction hole 31h to be introduced is provided. In other words, on the peripheral surface of the inner liner 13, inner secondary air introduction holes 29 h and inner secondary air introduction holes 31 h are alternately provided along the circumferential direction via the plurality of inner sleeves 29, 31.

  Here, on the upstream side (front side) of the secondary air introduction holes 25h, 27h, 29h, 31h in the combustion chamber 17, the mixture of fuel and primary air is excessively concentrated in a fuel-rich state (oxygen-deficient state). A primary combustion region A1 for combustion (primary combustion) is formed. Further, on the downstream side (rear side) of the secondary air introduction holes 25h, 27h, 29h, 31h in the combustion chamber 17, the mixture of the combustion gas and the secondary air from the primary combustion region A1 is in an oxygen excess state ( A secondary combustion region A2 for lean combustion (secondary combustion) in a fuel lean state is formed.

  The position P in the main flow direction of each secondary air introduction hole 25h, 27h, 29h, 31h (in the embodiment of the present invention, the position in the axial direction of the combustor liner 9) P is an average flow velocity (low) in the non-combustion state. The point where the flow (main flow) flowing at the NOx combustor 1 (average flow velocity) reaches in 1/3 hour of the residence time T staying in the combustion chamber 17, preferably in 1/4 hour of the residence time T It is set at a position on the upstream side from a position where it reaches and on a position on the downstream side from a position that reaches in 1/5 hour of the residence time T. The residence time is such that the position P in the main flow direction of each of the secondary air introduction holes 25h, 27h, 29h, 31h is set to a position downstream from the location where the arrival time T reaches 1/5 hour. This is because if it is set at a position on the upstream side of the position that reaches in 1/5 hour of T, it becomes difficult to sufficiently ensure the combustion stability at the time of low load. In addition, the part which reaches | attains with the residence time T in which the flow which flows at an average flow velocity in a non-combustion state stays in the combustion chamber 17 is an exit end of the combustor liner 9.

The total opening area of the plurality of secondary air introduction holes 25h, 27h, 29h, 31h is introduced from the plurality of secondary air introduction holes 25h, 27h, 29h, 31h with respect to the flow rate of all the air introduced into the combustion chamber 17. The ratio of the secondary air flow rate (secondary air flow rate ratio) is set to 20 to 70%, preferably 30 to 50%. The flow rate ratio of the secondary air is set to be 20% or more. When the flow rate is set to be less than 20%, the mixing of the combustion gas from the primary combustion region A1 and the secondary air is performed. This is because the dilution of the gas cannot be promoted, and it becomes difficult to reduce NOx (nitrogen oxide) during the operation of the low NOx combustor 1. On the other hand, the flow rate ratio of the secondary air is set to be 70% or less. If it is set to exceed 70%, the combustion effect in the secondary combustion region A2 is not sufficiently exhibited. This is because it becomes difficult to reduce emissions of CO (carbon monoxide) and THC (unburned hydrocarbons).

  The plurality of outer secondary air introduction holes 25h, 27h and the plurality of inner secondary air introduction holes 29h, 31h are alternately arranged along the circumferential direction so as not to face each other. However, when the flow rate ratio of the secondary air is set to be 40% or less, the plurality of outer secondary air introduction holes 25h and 27h and the plurality of inner secondary air introduction holes 29h and 31h are opposed to each other. It may be arranged as follows. The opening area of the outer secondary air introduction hole 25h is set to be larger than the opening area of the outer secondary air introduction hole 27h, and the opening area of the inner secondary air introduction hole 29h is It is set to be larger than the opening area of the air introduction hole 31h. In other words, the opening areas of the secondary air introduction holes 25h and 29h on the side close to the fuel injection valve 19 are larger than the opening areas of the secondary air introduction holes 27h and 31h on the side far from the fuel injection valve 19. Is set.

  Then, the effect | action and effect of embodiment of this invention are demonstrated.

  Fuel is injected as a conical spray flow S into the combustion chamber 17 by the plurality of fuel injection valves 19, and primary air is introduced as a swirl flow from the plurality of swirlers 23. As a result, in the primary combustion region A1, the air-fuel mixture of fuel and primary air is excessively burned in a fuel rich state to generate combustion gas. The fuel in the air-fuel mixture is ignited by the spark plug immediately before the air-fuel mixture of fuel and primary air is combusted.

  Subsequently, a large amount of secondary air is introduced into the combustion chamber 17 from the plurality of outer secondary air introduction holes 25h, 27h and the plurality of inner secondary air introduction holes 29h, 31h with high penetration (radial penetration). Is done. As a result, the combustion gas and the secondary air are rapidly mixed between the primary combustion region A1 and the secondary combustion region A2, and the mixture of the combustion gas and the secondary air is diluted in the oxygen excess state in the secondary combustion region A2. Combustion produces combustion gas and discharges it from the combustor liner 9.

  Here, a plurality of outer secondary air introduction holes 25 h and 27 h are provided on the outer peripheral surface of the outer liner 11 via a plurality of outer sleeves 25 and 27, and a plurality of inner secondary air introduction holes 29 h and 31 h are provided in the inner liner 13. Since the circumferential surface is provided with a plurality of inner sleeves 29 and 31, the penetration degree of the secondary air introduced into the combustion chamber 17 can be set high as described above. In addition, since the plurality of outer secondary air introduction holes 25h and 27h and the plurality of inner secondary air introduction holes 29h and 31h are alternately arranged along the circumferential direction so as not to face each other, a plurality of outer secondary air introduction holes It is possible to prevent a strong reverse flow due to a collision between the secondary air introduced from the air introduction holes 25h and 27h and the secondary air introduced from the plurality of inner secondary air introduction holes 29h and 31h. Further, the opening area of the secondary air introduction holes 25h and 29h on the side close to the fuel injection valve 19 is set to be larger than the opening area of the secondary air introduction holes 27h and 31h on the side far from the fuel injection valve 19. Therefore, secondary air is introduced into the combustion chamber 17 according to the concentration distribution of fuel in the circumferential direction in the combustion chamber 17.

  By continuously performing the rich combustion in the primary combustion region A1 and the lean combustion in the secondary combustion region A2, the turbine (not shown) disposed downstream of the low NOx combustor 1 is driven. The operation of the jet engine can be continued.

  Here, since the total opening area of the plurality of secondary air introduction holes 25h, 27h, 29h, 31h is set so that the flow rate ratio of the secondary air is 20 to 70%, each secondary air introduction hole is Specifically, by bringing 25h, 27h, 29h, 31h closer to the fuel injection valve 19, the position P in the main flow direction of each of the secondary air introduction holes 25h, 27h, 29h, 31h is located upstream from the predetermined position. The NOx, CO, and THC emissions during operation of the low NOx combustor 1 can be reduced by setting to the position. In other words, while ensuring the combustion stability by the primary combustion region A1, while reducing the amount of NOx, CO, and THC emissions during operation of the low NOx combustor 1, the secondary combustion region in the combustion chamber 17 A2 can be sufficiently secured.

  Therefore, according to the embodiment of the present invention, the combustion chamber is secured while the combustion stability is ensured by the primary combustion region A1, and the emission amount of NOx, CO, and THC during the operation of the low NOx combustor 1 is reduced. 17 can sufficiently secure the secondary combustion region A2, so that smoke (smoke) discharged by the rich combustion in the primary combustion region A1 is sufficiently burned (lean combustion) in the secondary combustion region A2, thereby reducing the low NOx. Smoke emission during operation of the combustor 1 can be reduced. Therefore, it is possible to achieve both the reduction of NOx, CO, and THC emissions during the operation of the low NOx combustor 1 and the reduction of smoke emissions.

  In particular, it is possible to prevent a strong back flow caused by a collision between the secondary air introduced from the plurality of outer secondary air introduction holes 25h and 27h and the secondary air introduced from the plurality of inner secondary air introduction holes 29h and 31h. It is possible to prevent the primary combustion region A1 from being diluted and the flame temperature in the primary combustion region A1 from becoming locally high. Further, since secondary air is introduced into the combustion chamber 17 according to the concentration distribution of fuel in the circumferential direction in the combustion chamber 17, the homogeneity (mixing degree) of the air-fuel mixture in the secondary combustion region A2 is increased. Can do. Therefore, the NOx emission amount during the operation of the low NOx combustor 1 can be sufficiently reduced.

  Specifically, as a result of the combustion test, it was confirmed that the NOx emissions and smoke emissions during operation of the low NOx combustor 1 can be reduced to less than half of the ICAO regulation value (2004 enforcement standard). It was also confirmed that the outlet temperature non-uniformity PTF (PTF = (combustor outlet maximum temperature−combustor outlet average temperature) / combustor average temperature rise) of the low NOx combustor 1 can be made smaller than 0.2.

  The present invention is not limited to the description of the above-described embodiment. For example, the technical idea applied to the annular type low NOx combustor 1 is applied to a can type low NOx combustor (not shown). In addition, various embodiments can be implemented. Further, the scope of rights encompassed by the present invention is not limited to these embodiments.

A1 Primary combustion region A2 Secondary combustion region G Standing vortex S Spray flow 1 Combustor 3 Combustor case 5 Outer case 7 Inner case 9 Combustor liner 11 Outer liner 13 Inner liner 15 Partition 17 Combustion chamber 19 Fuel injection valve 21 Fuel supply pipe 23 Swirler 25 Outer sleeve 25h Outer secondary air introduction hole 27 Outer sleeve 27h Outer secondary air introduction hole 29 Inner sleeve 29h Inner secondary air introduction hole 31 Inner sleeve 31h Inner secondary air introduction hole

Claims (4)

An RQL-type low NOx combustor that is used in a gas turbine and generates combustion gas by burning a mixture of fuel and air while reducing NOx emissions,
A combustor liner having a partition on the upstream side and having a combustion chamber for burning the air-fuel mixture inside;
A fuel injection valve provided in the partition wall for injecting fuel into the combustion chamber;
A primary air introduction member that is provided in the partition wall and introduces primary air into the combustion chamber;
A plurality of secondary air introduction holes for introducing secondary air into the combustion chamber are provided in the circumferential surface of the combustor liner at intervals along the circumferential direction, and upstream of the secondary air introduction hole in the combustion chamber. A primary combustion region for over-burning the mixture of fuel and primary air in the fuel-rich state is formed on the side, and the downstream side of the secondary air introduction hole in the combustion chamber from the primary combustion region A secondary combustion region for lean combustion of the mixture of combustion gas and secondary air in an oxygen-excess state is formed,
The mainstream direction position of the secondary air induction hole is set at a position where the flow flowing at an average flow rate in the non-combustion state is reached in 1/5 1/3 hours of dwell time staying in the combustion chamber, a plurality The total opening area of the secondary air introduction holes is such that the ratio of the flow rate of secondary air introduced from the plurality of secondary air introduction holes to the flow rate of all the air introduced into the combustion chamber is 20 to 70%. An RQL low NOx combustor that is set to be The combustor liner exhibits a hollow ring, the partitions are each other by an annular shape, the fuel injection valve is provided with a plurality at intervals along the circumferential direction on the partition wall, in the primary air introduction member is the partition wall Provided around each fuel injection valve,
The plurality of secondary air introduction holes are circumferentially provided on the outer peripheral surface of the combustor liner and at a plurality of outer secondary air introduction holes provided at intervals along the circumferential direction, and on the inner peripheral surface of the combustor liner. A plurality of inner secondary air introduction holes provided at intervals along the direction, and the plurality of outer secondary air introduction holes and the plurality of inner secondary air introduction holes are not opposed to each other. are staggered along the circumferential direction, the low NOx combustor RQL method according to claim 1. An opening area of the outer secondary air introduction hole on the side close to the fuel injection valve is set to be larger than an opening area of the outer secondary air introduction hole on the side far from the fuel injection valve, and the fuel injection opening area of the inner secondary air inlet holes near the valve side is set to be larger than the opening area of the inner secondary air introducing hole on the far side to the fuel injection valve, in claim 2 RQL type low NOx combustor as described. Each secondary air introduction hole has on the inner side of the sleeve provided in the combustor liner, the low NOx combustor RQL method according to any one of claims 1 to 3.

Images