JPS5912724B2 - Air driven atmosphere control burner - Google Patents

Description

[Detailed Description of the Invention] This invention enables high-temperature air preheating suitable for hot blast furnaces for blast furnaces and other large-scale regenerative heat exchangers, and allows the combustion atmosphere to be freely controlled from oxidizing to neutral or reducing. This invention relates to an air-driven atmosphere control burner that enables stable combustion even with changes in fuel flow rate.

Conventionally, as a burner for a large regenerative heat exchanger, a burner is installed in an air supply pipe 2 connected to a combustion chamber 1, as shown in a schematic front view in Fig. 1a and a schematic side view in Figs. , a gas supply pipe 3 and a swirl vane 4 are provided between the outer surface of the gas supply pipe 3 and the inner surface of the air supply pipe 2, and the air which has become a swirling flow by the swirl vane 4 in the combustion chamber 1 is A heat storage chamber (not shown) and a combustion chamber, as shown in a schematic longitudinal sectional front view in FIG. 2a and a schematic cross-sectional plan view in FIG. The combustion chamber 5 is separated from the combustion chamber 5, and air and gas from an air supply pipe 6 and a gas supply pipe 7 connected to the lower part of the combustion chamber 5 are supplied to each header 6 provided at the lower part of the combustion chamber 5.
a, 7a, and then from the headers 6a, 7a, independently pass through slits separated from each other by ceramic partition walls (indicated by a and b in the figure, respectively) to open the slit openings. After merging and mixing in section 8,
There are some that are made to burn.

However, in the case shown in Figures 1a and 1b, oscillatory combustion tends to occur due to changes in the gas calorie, air-fuel ratio, and flow rate, and combustion is unstable. It is difficult to control the atmosphere widely and stably.

In addition, what is shown in FIGS. 2a and b are the same as those shown in FIGS.
This is an improved version of the combustion instability shown in , and although it is true that oscillatory combustion does not occur even if the combustion load is increased, drifting tends to occur between the introduction section and the jet section, which impairs the mixing effect. Due to the poor mixing effect of gas and air, the flame length changes drastically in response to fluctuations in combustion load, gas calorie fluctuations, and air-fuel ratio.
Since the partition walls are made of ceramic, there is a problem with the sealing between gas and air, and there is also a risk of explosion if the air is preheated to a high temperature.

Due to the magnetic force, a rotating burner as shown in a plan view in FIG. 3 and in a vertical cross-sectional view in FIG. 4 has been proposed (see Japanese Patent Publication No. 46881/1981).

A port section 10 is provided at the lower part of the combustion chamber 9, and an air supply pipe 11 and a gas supply pipe 1 are connected to the port section 10.
The burner is equipped with a multi-stage air blowing opening 13 and a required number of gas blowing openings 14 for blowing in air and gas from both the supply pipes 11 and 12, which are connected to each other and open inside the supply pipes 11 and 12, respectively. However, since the opening area of the air blowing opening 13 and the gas blowing opening 14 are approximately equal, it is possible to obtain stable combustion against fluctuations in combustion load and air-fuel ratio. There is a problem in that it is difficult to control the combustion atmosphere of LPG gas, etc.

Therefore, this invention solves the above problems, makes it possible to preheat high temperature air, and makes it possible to widely control the combustion atmosphere.
Moreover, it was designed to provide an air-driven atmosphere control burner that enables stable combustion even when the fuel flow rate changes. The cylindrical body has a required number of holes for gas nozzles in the body near the combustion opening at the tip thereof, and an air introduction opening in the body at the base end thereof, Inside the cover, a space between the outer surface of the cylindrical body and the inner surface of the cover is provided with a chamber for supplying gas to the hole for the gas nozzle, and a chamber for supplying air to the air introduction opening. A partition is provided to separate the gas nozzle into a gas chamber, and the injection force direction of the gas nozzle hole is adjusted to
It is characterized in that it is deviated by a predetermined angle from a direction perpendicular to the axis of the cylindrical body toward the tip of the cylindrical body and in a plane perpendicular to the axis of the cylindrical body.

The present invention will be described below based on embodiments and with reference to the drawings.

FIG. 5 is a longitudinal cross-sectional view of a burner to which the present invention is applied, FIG. 6A is a cross-sectional view taken along the line AA in FIG. 5, and FIG. 7 is a cross-sectional view taken along the line B-B in FIG.

As shown in the figure, 15 is a cover made of ceramic tiles that communicates with a combustion chamber (not shown), and (7) three cylindrical bodies 16 are provided inside the cover 15.

The cylindrical body 16 has eight holes 17 for gas nozzles arranged at equal intervals around the circumference in the body near the combustion opening at the tip thereof, and in the body near the combustion opening at the base end. An opening 1B for introducing air is provided in the section.

Further, a space is formed between the outer surface of the cylindrical body 16 and the inner surface of the cover 15, and this space is divided into a chamber 19 for supplying gas to the gas nozzle hole 17, and a chamber 19 for supplying gas to the gas nozzle hole 17, and a chamber 19 for supplying gas to the gas nozzle hole 17, and A partition 21 is provided inside the cover 15 to separate the opening 18 from the chamber 20 for supplying air.

The cover 15 is formed with a gas supply port 22 communicating with the chamber 19 and an air supply port 23 communicating with the chamber 20, and the compartment 19. 20 are adapted to be supplied with gas and air, respectively.

The injection force direction of the gas nozzle hole 17 is
6 in the direction perpendicular to the axis of the cylindrical body 16, and in a plane perpendicular to the axis of the cylindrical body 16 at a predetermined angle.

The former deviation angle α is preferably in the range of 25 to 30°, and the latter deviation angle β is preferably in the range of 15 to 25°.

forming a chamber 19 for supplying gas to the hole 17;
A metal plate 24 is placed over the cylindrical body 16 except for the inner surface (excluding the hole 17), thereby further keeping the chamber 19 airtight. ing.

A throttle opening 25 is provided inside the cylindrical body 16 at its axially intermediate portion, and this throttle opening 25 further improves the rectifying effect of the air from the base end to the distal end of the cylindrical body 16; It is designed to increase the backfire prevention effect.

Note that the gas nozzle holes 17 may be provided in two stages with eight holes each approaching in the axial direction of the cylindrical body 16. In this case, when viewed from the axial direction of the cylindrical body 16, the holes 17 are arranged around the circumference of the cylindrical body 16. In addition, it is preferable that the holes 17 in the second stage are located in the center between the adjacent holes 17 in the first stage (see FIG. 6).

With such a configuration, the air supplied from the air supply port 23 through the chamber 20 and the opening 18 into the cylindrical body 16 is ejected from the tip opening of the cylindrical body 16, and at this time, the air is ejected from the gas supply port 22. Gas force ζ ejected near the tip opening in the cylindrical body 16 through the chamber 19 and the hole 17
By specifying the direction of the injection force, the fuel mixes efficiently with the air and burns.

As a result of many operations, the flame form was determined by the excess air ratio m and the gas flow momentum Pg for each cylinder.
VgQg (Pg: gas density (m2/5ec), Vg: gas nozzle flow rate (m/5ec), Qg: ejected gas amount (m3
/5ec)), the airflow momentum PaVaQ
a (Pa: air density (kg/m3), Va: air flow velocity (
m/sec), Qa: Volume of ejected air (m3/5
ec)) (momentum ratio) φ,
It was possible to classify into each region as shown in FIG. 8, which is a diagram showing the relationship between the momentum ratio and the excess air ratio m.

In the figure, A is a complete ring formation area, B is a radial ring formation area,
C is the ring fluctuation area, D is the ring non-formation area, and regarding flames, E indicates the transition flame area, the right side of this transition flame area E is the blue flame area, and the left side is the bright flame area. ing.

Combustion continues completely in each of these regions, but the opening diameter D of the cylindrical body is adjusted so that the combustion conditions are within the blue flame region, that is, regions A, B, and C, especially the complete ring formation region A. , and the gas nozzle diameter d are preferably set.

Therefore, the momentum ratio φ is preferably 0.5 or more. For example, if the excess air ratio m is 1.0, if the momentum ratio φ is 4.0, the combustion condition range can be maintained even if the excess air ratio changes greatly. It is possible to achieve a nearly blue flame range, and the combustion atmosphere control range can be extremely widened.

As described above, since the flame form can be classified only by the excess air ratio m and the momentum ratio φ, it is clear that natural gas, LPG, etc., which have a large theoretical air amount, can be sufficiently applied.

In addition, a formula for determining the opening diameter of each cylinder was derived based on a large amount of operational data.

Suna [However, D = opening diameter of one cylinder (rnm) Burning amount per H2 cylindrical body (K at/hr ) T: Air preheating temperature (’K) C: Air dynamic viscosity coefficient (m2/5ec)) was derived.

For example, using three cylinders, H=20X106K
cat/hr (using city gas) and T2900°C, the opening diameter of each cylindrical body is approximately 1300 mm.

Furthermore, in this case, for example, the excess air ratio m is 1.0 and the momentum ratio φ is 4.0.
Assuming that eight gas nozzle holes are provided with a deflection angle α of 27° and a deflection angle β of 20°, the gas nozzle diameter d is determined as follows.

That is, the amount of ejected gas Qg per cylindrical body is 4.
53 X 1 O3Nm3/hr, gas density Pg
is 0.786 kg/Nm3, and the amount of air emitted Qa is 2.04.
X 10' Nm3/hr, and the air density Pa is 1
．． Under operating conditions of 29 kg/N m'', the air flow velocity Va is: and the air flow momentum PaVaQa is 1.34
X102 (N) force, -force, gas flow velocity Vg is, and gas flow momentum PgVgQg is 23.4
/d2 (N).

Therefore, the momentum ratio φ is as follows, so for φ24.0, d=0.21 (m),
That is, the gas nozzle diameter is 21 crrL.

As explained above, in this invention, stable combustion is possible even with changes in the air-fuel ratio, combustion amount, and gas power port IJ -, and the combustion atmosphere can be changed from oxidizing to neutral to neutral. It is possible to provide a burner whose reducing properties can be freely controlled.

[Brief explanation of drawings]

Figure 1a is a schematic front view of a burner for a conventional large-scale regenerative heat exchanger, Figure 1 is a schematic side view of the same, and Figure 2a is a schematic longitudinal cross-section of another burner for a conventional large-scale regenerative heat exchanger. Side view,
Fig. 2 is a schematic cross-sectional plan view of the same, Fig. 3 is a plan view of the conventional rotary burner, Fig. 4 is a longitudinal sectional view of the same, Fig. 5 is a longitudinal sectional view of the burner to which the present invention is applied, and Fig. 6 is an illustration. is a cross-sectional view taken along line A-A in Figure 5, Figure 6 is a cross-sectional view of the cylindrical body, and Figure 7 is B in Figure 5.
-B sectional view, FIG. 8 is a diagram showing the flame form in relation to the momentum ratio and the excess air ratio. 1.5, 9... Combustion chamber, 2.6.11...
...Air supply piping, 3. 7. 12... Gas supply piping, 4... Swivel vane, 6at7a...
Header, 8...Slit opening, 10...
... Port section, 13 ... Air blowing opening, 14
...Gas blowing opening, 15...Cover 1
6... Cylindrical body, 17... Hole for gas nozzle, 18... Opening for air introduction, 19...
... A chamber for supplying gas to the hole 17, 20...
... A chamber for supplying air to the opening 18, 21...
...Partition, 22...Gas supply port, 23...
...Air supply port, 24, curved metal plate, 25...
・Aperture opening, A...Complete ring formation area, B...
... Radiation ring formation region, C ... Ring fluctuation region, D ... Rinse formation region, E ... Transition flame region.

Claims (1)

[Scope of Claims] 1. A cover made of ceramic tiles, and at least three cylindrical bodies provided inside the cover, and each of the cylindrical bodies has a body portion near a combustion opening at its tip,
A required number of gas nozzles and holes are provided, and an opening for introducing air is provided in the body at the proximal end thereof, and the hole is provided inside the cover between the outer surface of the cylindrical body and the inner surface of the cover. A partition is provided to divide the space into a chamber for supplying gas to the gas nozzle hole and a chamber for supplying air to the air introduction opening, and the injection force of the gas nozzle hole is The air-driven type is characterized in that the direction is deviated by a predetermined angle from a direction perpendicular to the axis of the cylindrical body toward the tip of the cylindrical body and in a plane perpendicular to the axis of the cylindrical body. Atmosphere control burner.