JP4355270B2 - Combustion burner and combustion apparatus equipped with combustion burner - Google Patents

Description

  The present invention relates to a combustion burner for reducing NOx and improving combustion efficiency, and further relates to a combustion apparatus including a combustion burner, for example, a boiler, a heating furnace, or a hot air generating furnace.

  FIG. 3 shows a configuration example of a burner for solid fuel related to the prior art. In FIG. 3, 1 is a mixed fluid of solid fuel and transport primary gas, 2 is a mixed fluid jet nozzle, 3 is a furnace, 101 is a flame holding ring, 102 is a baffle plate, 103 is a tertiary gas swirler, and 104 is a tertiary gas. A guide plate, 105 is a secondary gas, 106 is a tertiary gas, 107 is a jet flow of fuel and a discharge gas, 108 is a secondary gas jet flow, 109 is a tertiary gas jet flow, and 110 is a circulating vortex .

  In the prior art shown in FIG. 3, a mixed gas nozzle 2 defining a mixed fluid flow path in which a mixed fluid 1 containing a solid fuel and a transporting primary gas flows toward a furnace 3, a secondary gas 105 and a tertiary gas A gas supply nozzle that defines a gas flow path through which the gas 106 flows. The secondary gas 105 and the tertiary gas 106 flow around the mixed gas 1. A flame holding ring 101 is provided at the front end of the outlet of the gas mixture nozzle 2, and a baffle plate 102 that changes the flow direction of the secondary gas 105 to the outside is installed at the front end.

  Ignition is possible from the vicinity of the burner by the effect of the circulating vortex 110 formed in the wake of the baffle plate 102. The flow path of the peripheral tertiary air 103 is widened outward by the guide plate 104, delays the mixing of air into the flame center, and suppresses the generation of nitrogen oxides (NOx) by combustion under air-deficient conditions. ing. The baffle plate 102 suddenly changes the direction of the secondary gas 105 to the outside. However, since the surrounding gas is entrained in this outward flow, the circulating vortex 110 approaches the burner and promotes ignition from the burner. is doing.

The details of the prior art as shown in FIG. According to this Patent Document 1, the flame holding ring and the baffle plate are intended to improve the flame holding property and reduce NOx, that is, the pulverized coal flame is stably ignited from the base by the flame holding ring, By supplying secondary air and tertiary air to the outside slightly, the flame on the shaft core is used as a reducing flame to reduce NOx, and after that, it is mixed and diffused with combustion air to achieve complete combustion. In other words, in patent document 1, while suppressing that a pulverized coal spread | diffuses outside by a flame-holding ring, a vortex | eddy current is formed in the flame-holding ring vicinity, a ignitability is improved, a flame-holding effect is improved, and a reduction area is ensured. It is what is generated.
JP-A-62-196511

  However, as a conventional technique, in the combustion burner shown in FIG. 3 and the combustion burner shown in Patent Document 1 described above, a part of the oxygen-containing gas for combustion is used as the secondary gas, and the flow rate is the pressure of the secondary gas. Depending on the shape of the baffle plate, there is a limit to speeding up the secondary gas jet flow. On the other hand, since the formation of the circulating vortex greatly depends on the outward flow velocity of the secondary gas, the size of the circulating vortex naturally has a limit.

  An object of the present invention is to provide a combustion burner that increases the momentum of secondary air to increase the circulation vortex to promote ignition, thereby reducing NOx and improving combustion efficiency.

In order to solve the above problems, the present invention mainly adopts the following configuration.
A mixed fluid jet nozzle that supplies a mixed fluid of solid fuel and a first carrier gas to a furnace, and a second gas flow path that surrounds the mixed fluid jet nozzle and supplies a second combustion oxygen-containing gas to the furnace. And a third gas flow path for supplying a third combustion oxygen-containing gas to the furnace outside the second gas flow path,
The second combustion oxygen-containing gas ejection member is a ring-shaped supply header attached to the tip of the mixed fluid ejection nozzle, and the ring-shaped supply header is provided with an ejection nozzle hole on its outer peripheral side, The second combustion oxygen-containing gas having a pressure higher than that of the third combustion oxygen-containing gas is ejected from the ejection nozzle hole toward the radially outer side of the ring shape, and the ring-shaped supply header is The outer peripheral side excluding the ejection nozzle hole forms a tapered shape, and the ejection flow of the third combustion oxygen-containing gas is guided by the tapered shape so as to be separated from the flow direction axis of the mixed fluid. And

Further, in the combustion burner, the second combustion oxygen-containing gas is configured to use air pressurized by a fan and preheated with exhaust gas from the furnace. Further, the flow rate ratio between the second combustion oxygen-containing gas and the third combustion oxygen-containing gas is variable. The flow rate ratio is variable depending on the load of the furnace or the NOx value of the furnace exhaust gas.

  By introducing the high-pressure second oxygen-containing gas for combustion, the circulation vortex increases due to the enhancement of the entrainment effect, and ignition can be promoted. Further, by promoting ignition, reduction of NOx and improvement of combustion efficiency are promoted.

  A combustion burner according to an embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a diagram showing a configuration of a combustion burner according to a first embodiment of the present invention and a flow of a mixed gas flow and a combustion gas flow, and FIG. 2 is a diagram for combustion according to a second embodiment of the present invention. It is a figure which shows the structure of a burner, the flow of a mixed gas flow, and the gas flow for combustion.

  1 and 2, 1 is a mixed fluid of a solid fuel and a first carrier gas, 2 is a mixed fluid injection nozzle, 3 is a furnace, 4 is a low pressure third combustion oxygen-containing gas, and 5 is a high pressure. 2nd oxygen gas for combustion, 6 is a high pressure 2nd oxygen gas supply pipe for combustion, 7 is a high pressure 2nd oxygen gas supply header for combustion, 8 is a high pressure 2nd oxygen gas for combustion A gas jet nozzle, 9 is a high-pressure second combustion oxygen-containing gas jet flow, 10 is a circulating vortex, 11 is a solid fuel and a first transport gas jet flow, and 12 is a low-pressure third combustion oxygen-containing gas. Represents a jet flow.

  In FIG. 1, the combustion burner according to the first embodiment of the present invention is a mixture that defines a mixed fluid path in which a mixed fluid 1 containing solid fuel and a first carrier gas flows toward a furnace 3. The gas nozzle 2 is attached to the front end portion of the gas mixture nozzle on the furnace 3 side, and the second combustion containing pressure is relatively or relatively high (relative to the third combustion oxygen-containing gas described later). A ring-shaped supply header 7 for supplying oxygen gas and a gas flow path through which the low pressure third combustion oxygen-containing gas 4 flows relative to (relative to the second combustion oxygen-containing gas described above) are defined. A gas supply nozzle.

  The ring-shaped supply header 7 showing the characteristics of the present embodiment is formed with a jet nozzle 8 at a predetermined interval along the outer peripheral portion (illustrated example in FIG. 1) or over the entire outer peripheral portion. A second oxygen-containing gas for combustion having a high or relatively high pressure is supplied through the supply pipe 6. Then, the high-pressure second oxygen-containing gas for combustion 5 forms a jet 9 outwardly in the radial direction of the ring-shaped supply header 7 through the jet nozzle 9.

  The mixed gas circulation vortex 10 formed in the vicinity of the ring-shaped supply header 7 is entrained by the jet 9 to generate a so-called entrainment effect. Here, by the forced outward jet formation by the second oxygen-containing gas for combustion, the surrounding gas, that is, the circulating vortex 10 is entrained, and the magnitude of the accompanying action is governed by the momentum of the jet. . The greater the flow rate or the higher the flow velocity, the greater the momentum and the greater the entrainment.

  By increasing the momentum by increasing the speed of the second oxygen gas for combustion that is directed outward, the circulation vortex becomes larger and more high-temperature gas circulates to the vicinity of the burner to promote ignition. This leads to a reduction in NOx. That is, as the second oxygen-containing gas for combustion increases in pressure, the jet flow velocity increases, so the entrainment amount increases and the circulating vortex 108 becomes larger.

  Here, the supply source for supplying the relatively high-pressure second oxygen-containing gas for combustion may be air from a fan capable of supplying air at high pressure, and is supplied as combustion air for the burner. You may use the air from the fan of the secondary air 105 (refer FIG. 3). Moreover, the air from the fan which makes tertiary air (refer FIG. 3) high pressure may be sufficient. Specifically, it is possible to obtain high-temperature and high-pressure oxygen-containing gas for combustion by pushing air into an air preheater provided in the exhaust gas line of the furnace 3 and passing air from the ventilator.

  Further, a damper is provided in each of the flow paths of the second and third combustion oxygen-containing gases, and the flow rate ratio of the second and third combustion oxygen-containing gases can be varied by adjusting the opening of each damper. can do. At this time, the NOx value obtained by the gas analyzer provided in the exhaust gas line of the furnace 3 can be adjusted. By changing the flow rate ratio, the size of the circulating vortex is changed to change the NOx generation value. Further, the flow rate ratio may be varied depending on the load of the furnace, and in this case, the combustion efficiency is changed by varying the flow rate ratio.

  Next, in the combustion burner according to the second embodiment of the present invention, as shown in FIG. 2, the ring-shaped supply header 7 functions as a guide member 7a that guides the third combustion oxygen-containing gas 4 to the outside. It has a shape that plays. That is, as compared with the ring-shaped supply header in the first embodiment, the outer peripheral structure adopts a taper shape to guide the third combustion oxygen-containing gas 4 to be ejected to the outside of the ring axis. It is. Since the combustion oxygen-containing gas 4 is effectively spread by the guide member 7a, the circulation vortex 108 becomes larger and ignition is promoted. 2 are the same as those in FIG. 1 except for the guide member 7a.

  The secondary air passage in the prior art shown in FIG. 3 has a duct shape, but as shown in FIGS. 1 and 2, in this embodiment, the high-pressure second oxygen-containing gas for combustion is used. Is supplied to the ring-shaped supply header 7 because the gas is at a high pressure, the supply pipe 6 is used. Therefore, the burner insertion diameter opened on the furnace side wall can be reduced.

  Further, by adopting a ring-shaped supply header as indicated by reference numeral 7 in FIG. 1 and reference numeral 7 a in FIG. 2, the second combustion oxygen-containing gas having a high pressure is ejected substantially uniformly in the radial shape of the circular burner. Thus, stable ignition and burner flame can be formed.

It is a figure which shows the structure of the combustion burner which concerns on the 1st Embodiment of this invention, the flow of mixed gas flow, and the flow of combustion gas. It is a figure which shows the structure of the combustion burner which concerns on the 2nd Embodiment of this invention, and the flow of mixed gas flow and combustion gas flow. It is a figure which shows the structure of the combustion burner regarding a prior art, and the flow of mixed gas flow and combustion gas flow.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mixed fluid of solid fuel and 1st conveyance gas 2 Mixed fluid injection nozzle 3 Furnace 4 Low pressure 3rd oxygen-containing gas for combustion 5 High pressure 2nd oxygen-containing gas for combustion 6 High pressure 2nd for combustion Oxygenated gas supply pipe 7 High pressure second oxygenated gas supply header for combustion 8 High pressure second oxygenated gas jet nozzle for combustion 9 High pressure second oxygenated gas jet for combustion 10 Circulating vortex 11 Solid fuel And the first carrier gas jet flow 12 Low pressure third combustion oxygen-containing gas jet flow 101 Flame holding ring 102 Baffle plate 103 Tertiary gas swirler 104 Tertiary gas guide plate 105 Secondary gas 106 Tertiary gas 107 Fuel and carry-out Jet flow 108 secondary gas jet flow 109 tertiary gas jet flow 110 circulating vortex

Claims (5)

A mixed fluid jet nozzle that supplies a mixed fluid of solid fuel and a first carrier gas to a furnace, and a second gas flow path that surrounds the mixed fluid jet nozzle and supplies a second combustion oxygen-containing gas to the furnace. And a third gas flow path for supplying a third combustion oxygen-containing gas to the furnace outside the second gas flow path,
The second combustion oxygen-containing gas ejection member is a ring-shaped supply header attached to the tip of the mixed fluid ejection nozzle,
The ring-shaped supply header is provided with a jet nozzle hole on its outer peripheral side,
The second combustion oxygen-containing gas having a pressure higher than that of the third combustion oxygen-containing gas is ejected from the ejection nozzle hole toward the radially outer side of the ring shape,
Furthermore, the ring-shaped supply header forms a tapered shape on the outer peripheral side excluding the ejection nozzle hole,
The third burner oxygen-containing gas is guided by the taper shape so as to be away from the axial center of the flow direction of the mixed fluid. In claim 1 ,
As the second oxygen-containing gas for combustion, air that has been pressurized with a fan and preheated with exhaust gas from the furnace is used. In claim 1 or 2 ,
A combustion burner characterized by varying a flow rate ratio between the second combustion oxygen-containing gas and the third combustion oxygen-containing gas. In claim 3 ,
The combustion burner characterized in that the flow rate ratio is variable depending on the load of the furnace or the NOx value of the furnace exhaust gas. A combustion apparatus comprising the combustion burner according to any one of claims 1 to 4 .

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