KR20030047146A - Nozzle array for high combustion load - Google Patents

Abstract

PURPOSE: A method for optimizing the nozzle arrangement of a fuel injection device with many nozzles is provided to gain optimal flame, and to reduce the consumption of energy. CONSTITUTION: A fuel injection device with many nozzles has a nozzle array(N) uniting a plurality of heating nozzles(n1,n2,n3,n4). In the nozzle arrangement of the fuel injection device, because a center nozzle prevents flame from being stabilized and reduce the flow of blowout in nozzle separation distance(S) where maximum blowout is generated, the nozzles are arranged without the center nozzle to stabilize the flame.

Description

Optimal nozzle arrangement of multi-nozzle fuel ejector for high load combustion {Nozzle array for high combustion load}

The present invention relates to a nozzle array optimization method of a multi-nozzle fuel injection device, and more particularly, to provide a nozzle arrangement method for maximizing flame stability and energy efficiency in various types of flame ejection devices having a plurality of nozzles. It is about.

BACKGROUND ART Many nozzle fuel ejectors using a plurality of fuel ejection outlets are widely used in the industry in burners for various uses in homes and industries, burners for heaters, and burners for industrial machines.

Combustion by such a plurality of fuel outlets can reduce the size of the combustion chamber by reducing the length of the flame compared to a single nozzle is widely used in the production of combustion chambers and burners throughout the industry.

However, in the case of flames by such a plurality of dense fuel outlets, there is a limitation in raising the combustion load due to the problem of stabilization of the flame. On the other hand, it is known from previous studies that flames with multiple nozzles influencing each other are more effective in flame stability and pollutant reduction than the characteristics of a single nozzle.

Previous research has shown that flames are more stable than single nozzles by using multiple nozzles. When five nozzles are used, the flow rate of the flames is the same when the nozzle spacing is maintained at 28 to 32 times the nozzle diameter. 3.3 times more than a single nozzle in area.

In the optimum method of the nozzle arrangement of the multi-nozzle fuel ejector of the present invention, the most ideal method of arranging the multi-nozzle based on the effective arrangement of the nozzle which stabilizes the flame even at high load and the study of the flame characteristics according to the change of the nozzle interval (S / D) The purpose is to provide.

Figure 1 (a) to (g) is a schematic diagram of a nozzle arrangement configured for the experiment of the optimal method of the nozzle arrangement of the multiple nozzle flame ejection apparatus, such as the burner of the present invention.

Figure 2 is a schematic diagram of an experimental apparatus configured for the experiment of the optimal method of the nozzle arrangement of the multiple nozzle flame ejection apparatus, such as the burner of the present invention.

3 (a) and 3 (b) are graphs showing the flame blowing flow rate with respect to the nozzle arrangement of (a), (b), (c) and (d) of FIG.

4 (a), (b), (c), (d), and (e) show the shape of the turbulent flame for the nozzle arrangement (g) without the center arrangement of FIG. 1 S / D = 15.31 (a) Q = 300 [ml / min], (b) 400, (c) 500, (d) 600, (e) 700.

FIG. 5 shows the shape of the flame according to the change of the nozzle spacing and fixing the fuel flow rate per nozzle at 700 ml / min when the nozzle arrangement is circular, respectively (a) S / D = 15.31, (b) 18.37, (c) Photos in the state of 21.43, (d) 24.49, (e) 27.55.

Figure 6 (a) is a picture of the fuel and the flame injected from a plurality of nozzles taken by the Shylene method, (b) is a picture of the appearance of the actual flame.

Fig. 7 is a graph showing the flow rate of the flame blowing against the nozzle arrangement of the rectangle in which the center nozzle is removed in the matrix form and the matrix form.

Fig. 8 is a graph showing the flame flow rate at each nozzle distance in the case of (a) LPG and (b) methane (CH4) in the case where the nozzle arrangement is circular.

Explanation of symbols on the main parts of the drawings

B; LPG Bombe

C; Flow controller

CB; chamber

N; Nozzle Array

R; regulator

V; Control valve

In order to achieve the above object, the nozzle array optimization method of a multi-nozzle fuel ejecting apparatus such as a burner of the present invention;

In a multiple nozzle fuel ejection apparatus such as a burner in which a plurality of separate heating nozzles n 1, n 2, n 3, n 4, n 5,.

The arrangement of the nozzles (n1, n2, n3, n4, n5,...) Of the multiple nozzle flame ejection apparatus reduces the flow rate of the flame by preventing the center nozzle from stabilizing the flame in the region of the nozzle distance where the maximum flame occurs. Due to

In order to stabilize the flame in combustion by the multiple nozzles, the nozzle arrangement is arranged without the nozzle in the center area.

Another feature is that;

In a multiple nozzle flame ejection apparatus such as a burner in which a plurality of separate heating nozzles n1, n2, n3, n4, n5,.

In the arrangement of the plurality of nozzles n1, n2, n3, n4, n5,.

Further additional features of the optimal method of nozzle arrangement of a multiple nozzle flame ejection apparatus such as a burner of the present invention are;

In a multiple nozzle flame ejection apparatus such as a burner in which a plurality of separate heating nozzles n 1, n 2, n 3, n 4, n 5,.

When constituting the multiple nozzle flame ejection device in the ratio of eight circular shapes, the nozzles (n1, n2, n3, n4, n5,.,) Closest to the center of the nozzles (n1, n2, n3, n4, n5,...) The flame is stabilized even when the fuel flow rate at the nozzle exit is 204 [m / s] between a distance to the center of the nozzle (hereinafter referred to as S) is 15 to 28 times the nozzle diameter D.

With reference to the accompanying drawings, the configuration and operation of the optimum method of the nozzle arrangement of the multiple nozzle flame ejection apparatus such as the burner of the present invention will be described in more detail.

1 (a) to (g) is a schematic diagram of a nozzle arrangement configured for the experiment of the optimal method of nozzle arrangement of a multi-nozzle fuel injection device, such as a burner of the present invention, Figure 2 is a schematic diagram of an experimental apparatus configured for the present invention, 3 (a) and 3 (b) are graphs showing the flame blowing flow rate with respect to the nozzle arrangement of FIGS. 1 (a), (b), (c) and (d), and FIGS. 4 (a) and (b). ), (c), (d), and (e) fix the shape of the turbulent flame to (g) the nozzle arrangement without the center arrangement of FIG. 1 as S / D = 15.31 and the fuel flow rate per nozzle (a) Q = 300 [ml / min], (b) 400, (c) 500, (d) 600, (e) 700, taken from the state, FIG. 5 shows a fuel flow rate per nozzle of 700 ml / fixed to min and the shape of the flame according to the change of nozzle interval is shown in (a) S / D = 15.31, (b) 18.37, (c) 21.43, (d) 24.49, and (e) 27.55. (a) is a picture of the fuel and flames injected from the multiple nozzles by the Shylene method, (b) is a real A photo of the flame image, FIG. 7 is a graph showing the flame flow rate in a matrix nozzle array with a center nozzle and a rectangle nozzle without a center nozzle, and FIG. 8 shows a case where the nozzle array is circular (a) LPG, ( b) A graph showing the flame flow rate at each nozzle distance (S / D) in the case of methane (CH4).

An experimental apparatus configured to draw conclusions of an optimal method of nozzle arrangement of a multiple nozzle flame ejection apparatus such as a burner of the present invention will be described with reference to FIGS.

As shown in FIG. 1,

To characterize the turbulent liftedflame according to the arrangement of the nozzles (n1, n2, n3, n4, n5,.,), We compare them with 5 or 9 nozzles in the cross shape and 9 nozzles in the matrix form. In order to do this, an apparatus for conducting experiments on a quadrangular nozzle arrangement without a center nozzle (nc) and a quadrangular and circular arrangement in which nozzles are surrounded by a center is constructed.

Figure 1 (a) is a configuration having five nozzles (n1, n2, n3, n4, n5, ...) of the cross shape having a center nozzle (nc),

(b) shows four nozzle arrays without a center nozzle;

(c) is a nozzle arrangement having nine nozzles (n1, n2, n3, n4, n5, ...) having a center nozzle (nc),

(d) is a nozzle array having eight nozzles (n1, n2, n3, n4, n5,.

(e) is a matrix nozzle arrangement of nine nozzles (n1, n2, n3, n4, n5, ...) having a center nozzle,

(f) is a nozzle arrangement having eight nozzles (n1, n2, n3, n4, n5,.

(g) is an arrangement configuration having eight nozzles n1, n2, n3, n4, n5, ..., arranged in a circular shape, and constitutes the nozzle array N, respectively.

Such a nozzle array (N) is shown in Figure 2,

Experiment with LPG fed from LPG cylinder (B) as fuel and the fuel is connected to the regulator (R), the control valve (V), and the flow controller (C) is configured to be fed at any value,

The fuel flow is equalized through a stainless tube of 25.4 mm in diameter and 50 cm in length to act as the chamber CB, and the internal diameter 0.31 mm nozzles (nc, n1, n2, Through n3, n4, n5, ..., fuel is injected according to the shape of each nozzle array N described above.

The length from the burner plate P to which the nozzle array N is mechanically fixed to the nozzle tip T was set to 6.4 mm.

In all cases, the diameter D of the nozzles n1, n2, n3, n4, n5,... Is 0.31 mm, and the nozzle closest to the center of the nozzle (n1, n 2, n 3, n 4, n 5,...) The distance to the center of (n1, n2, n3, n4, n5,.,) is defined as 'S' as the nozzle separation distance.

As the experimental variable, the experiment was performed while varying the flow rate Q of the fuel supplied per nozzle and the S / D which dimensioned the nozzle-to-nozzle distance by the nozzle diameter for each nozzle arrangement type. The total flow rate supplied to CB) is divided by the number of multiple nozzles (n 1, n 2, n 3, n 4, n 5,...) As the flow rate flowing into a single nozzle having a diameter of 0.31 mm.

The results of experiments with the nozzle array N and the apparatus of the above-described configuration, and the optimum method of the nozzle arrangement of the multiple nozzle flame ejection apparatus such as the burner of the present invention thus obtained will be described in more detail with reference to FIG.

First of all, look at the results of each type of experiment.

(1) Comparison of flame blowing characteristics of cross-shaped array nozzles with or without center nozzles:

In the cross-shaped nozzle array (N), turbulent flame blowing characteristics with and without a center nozzle were compared.

First, the flame flow rate was investigated for a single nozzle having a diameter of 0.97 mm, which is similar to the sum of the areas of nine nozzles (n1, n2, n3, n4, n5, ...), and the total flow rate was 1575 [ml / min] flow rate in terms of single nozzle was 160 [ml / min].

When four nozzles (n1, n2, n3, n4) of cross shape are used in the graph of FIG. 3, the arrangement of five nozzles (n1, n2, n3, n4, n5,.,) With a center nozzle (nc) It can be seen that the flame flow rate increased in general rather than the form.

When eight nozzles (n1, n2, n3, n4, n5,.,) Are arranged in a cross shape without a center nozzle (nc), nine nozzles (n1) in a cross shape with a center nozzle (nc) in the same arrangement. The maximum blowout flow rate is higher in the range of S / D = 13 to 27 than in the arrangement of, n2, n3, n4, n5,.,), and the center nozzle is higher in other areas. appear.

In terms of maximizing flame flow, the array of nine nozzles (n1, n2, n3, n4, n5,.,) With a center nozzle (nc) has a flow rate of 430 [ml per nozzle at S / D = 22.6. / min], which increases the flow rate of the flame by 2.7 times than that of the single nozzle, and the eight crosses without the center nozzle (nc) have a flow rate of 567 [ml / min] per nozzle at S / D = 20. The rate of flame jump is 3.5 times higher than that of the case.

That is, near the maximum flame flow rate, the flame of the multiple nozzles in the absence of the center nozzle is more stable.

(2) Stability of round or square nozzle array flames:

Experiment with eight nozzles arranged in a square and a circle.

The state where S / D = 15.31 (a) Q = 300 [ml / min], (b) 400, (c) 500, (d) 600 and (e) 700, respectively, is shown in the photograph in FIG.

In the case of squares and circles, the flame characteristics are also similar in the form of similar nozzle arrangements.

4 is a photograph showing a change in flame shape when the nozzle arrangement is circular and the nozzle interval S / D is fixed at 15.31 and the flow rate per nozzle is increased from 300 ml / min to 700 ml / min.

In the picture of the figure, the flame can be divided into two parts, the flame body and the flame tail. It can be seen that as the flow rate increases, the length of the tag flame becomes longer.

In general diffusion flame, the mixture of fuel and air is thick inside the flame surface and tends to be thinner toward the outside, but near this flame tail, there is a lot of air inside the flame surface, and the fuel is outside the flame surface. Much rich.

This is because when the surrounding air is introduced with the fuel injected at high speed under the influence of the nozzle arrangement, air also flows into the center region from the nozzle arrangement.

Due to this phenomenon, the tail of the flame is formed, and the formed tail flame is thought to have an effect of preventing the flame from flying up to a high flow rate.

FIG. 5 shows the shape of the flame according to the change of the nozzle spacing and fixing the fuel flow rate per nozzle to 700 ml / min when the nozzle arrangement is circular.

Q = 700 [ml / min] (a) S / D = 15.31, (b) 18.37, (c) 21.43, (d) 24.49 and (e) 27.55.

When the nozzle dimension is gradually shortened by increasing the dimensionless nozzle spacing from (a) to (e), and the nozzle distance becomes more than a certain distance (S / D = 27.55 in the case of circular arrangement), the flame tail and flame body are distinguished. This becomes obscure.

On the other hand, if the dimensionless nozzle spacing is less than 15.31, there is no space for air to enter the center, so this tail flame does not appear, and the flame is blown at low flow rate.

In FIG. 6, (a) shows the fuel and flames injected from the multiple nozzles using the Shuleyn technique, and (b) shows the actual flame shape, using 8 square nozzle arrays (N) and Q = 500. ml / min and s / d = 16.

Fig. 7 shows the flame flow rate at each nozzle distance for the case where the nozzle arrangement is the matrix and the case where the rectangle is rectangular. The rectangular nozzle arrangement without center nozzle in S / D = 20 ~ 28 is more stable than the matrix type and there is no flame blowing.

Fig. 8 shows the flame flow rate at each nozzle distance in the case where the nozzle arrangement is circular. The case of (a) LPG and (b) methane (CH4) is shown, respectively.

(a) is a case where the fuel is LPG. In S / D = 15 to 28, no flame was blown even when the gage pressure inside the fuel supply pipe was raised to 3.5 atm, the maximum pressure of LPG at room temperature. In this case, choking occurs in the nozzle and the fuel flow rate at the nozzle outlet is 204 [m / s]. That is, the flame is very stable in this area.

Even if the fuel flow rate is increased by increasing the pressure of the reservoir of the fuel cylinder according to the load fluctuation, no flame is blown and combustion can be carried out even higher flow rate.

In (b), in the case of methane, the flow rate of the flame was measured according to the distance between nozzles (S / D). The flame blowing characteristics are similar to those of LPG and propane. Since methane requires less air to burn fuel completely than LPG or propane, the maximum flame flow rate is shown in the area where the nozzle distance (S / D) is small.

As a result of each of the experiments described above, the optimum method of the nozzle arrangement of the multiple nozzle flame ejection apparatus such as the burner of the present invention is concluded as follows.

(1) In the area of nozzle distance where maximal flame blowing occurs in many nozzles, the center nozzle plays a role to reduce the flow of flame by preventing the inflow of ambient air. That is, in order to stabilize the flame in the combustion by the multiple nozzles, the nozzle arrangement should exclude the nozzle in the center region.

(2) In the case where eight nozzles are arranged in a circle, flame blowing does not occur even when the fuel flow rate at the nozzle outlet is 204 [m / s] between the nozzle distances of 15 to 28, and the flame is maintained in a stable state.

The optimal nozzle arrangement of the multiple nozzle fuel ejection apparatus of the present invention as described above includes a plurality of nozzles in various burners such as industrial burners, domestic burners, gas stoves, steam boilers, marine boilers, and heating means mainly for liquid and gaseous fuels. By applying to a fuel injection device having a stable flame state can be obtained even without a separate additional device at high loads, it can be applied to a wide variety of applications such as energy saving and improved heating mode.

Claims (3)

In a multiple nozzle fuel ejection apparatus such as a burner in which a plurality of separate heating nozzles n 1, n 2, n 3, n 4, n 5,. The arrangement of the nozzles (n1, n2, n3, n4, n5,...) Of the multiple nozzle flame ejection device reduces the flow rate of the flame by preventing the inflow of ambient air in the region of the nozzle distance where the maximum flame occurs. Due to Optimal nozzle arrangement of a multiple nozzle fuel ejection device such as a burner, characterized in that the nozzle arrangement is configured to exclude the nozzle in the center area for stabilizing the flame in combustion by the multiple nozzles. In a multiple nozzle fuel ejection apparatus such as a burner in which a plurality of separate heating nozzles n 1, n 2, n 3, n 4, n 5,. Circular or 20 with a distance from the center of the nozzle (n1, n2, n3, n4, n5 ,.) to the center of the nozzle (n1, n2, n3, n4, n5 ,.) closest to the nozzle diameter Optimal method of nozzle arrangement in a multi-nozzle flame ejector such as a burner, characterized in that the flame is not generated even at a high load choked by the nozzle when arranged in a quadrangle of ˜28 times. In the case of methane, the nozzle array is optimized for a nozzle arrangement of multiple nozzle flame ejectors such as burners, characterized in that the nozzle spacing is optimized as a circular array having 12 to 16 times the nozzle diameter.