JPS62217010A - Gas pressure atomizing burner - Google Patents

Abstract

PURPOSE:To realize higher turn-down ratio at low atomizing medium ratio and small gas heat input ratio with no necessity of the flow control of gas by a structure wherein the passing cross section of the primary mixing chamber of fuel oil and gas is throttled into that of a mixing nozzle. CONSTITUTION:In a burner 10, oil, which flows in a fuel supply passage 15 and through an oil nozzle 17 as indicated with an arrow A, and atomizing fuel gas, which flows in a gas passage 16 and through a gas nozzle 18, respectively enter a primary mixing chamber 19. Next, the passing cross section toward a mixing nozzle is abruptly throttled in taper so as to develop the agitation due to the change of stream lines. Thus, the separation of liquid stream and air stream, which occurred so far, is prevented from developing and the mixing is accelerated in a mixing nozzle 20 and the jetting from a jet 21 under highly atomized state is realized. The position, at which the mixing chamber 19 is throttled to the nozzle 20, is set at the rear of a point, at which the oil nozzle 17 communicates with the mixing chamber 19.

Description

[Detailed description of the invention] [Industrial application field] FIELD OF THE INVENTION The present invention relates to an intermediate mixing gas pressure atomizing combustor.

[Prior Art] A gas pressure atomization combustion method uses relatively high-pressure fuel gas such as city gas as an atomization medium to atomize fuel oil.

For example, it is shown in Japanese Patent Laid-Open No. 511-149521. Compared to conventional steam spray or high-pressure air spray combustion, this gas pressure spray combustion method has the following advantages: (a) Pre-combustion of fuel gas promotes vaporization of fuel oil, improves combustion performance, and reduces CO2 emissions.
2. Low NOx combustion becomes OI, (b) the thermal efficiency of the furnace is improved because there is no need to feed low temperature steam or high pressure air into the furnace, (c) even at low combustion loads, the atomization medium Since the ratio is large, combustibility is not impaired and there are advantages such as a large turndown ratio.

[Problems to be Solved by the Invention] However, the combustion load by this gas pressure spray combustion is generally controlled by (a) constant gas pressure control or (b) constant gas-oil differential pressure control to control the flow rate on the oil side. This is done through control, but in any case, at low combustion loads, gas-only combustion is performed and a large turndown ratio is achieved by controlling the flow rate only on the gas side.

In general, spray combustors can be roughly divided into three types, as shown in Figure 5.
That is, there are (A) internal mixing type, (B) intermediate mixing type, and (C) external mixing type. These characteristics have advantages and disadvantages as shown in Table 4, but from the viewpoint of turndown characteristics, internal mixing type has a low combustion load and the oil/gas flow ratio and pressure ratio are small (hydraulic (lower than the gas pressure), pulsations occur on the oil side, and in some cases, a backflow phenomenon of gas toward the oil nozzle side may occur, making it unsuitable for a burner that achieves a high turndown ratio. However, in the case of a medium-mixing type, there is no oil pulsation or backflow at low combustion loads, which is convenient.

In order to maintain good atomization characteristics, the atomization medium ratio cannot be reduced. That is, in the case of an intermediate mix type spray combustor, the atomizing medium ratio is relatively large (in the case of a conventional intermediate mix type spray combustor, the gas/liquid mass flow rate ratio W G/W L・0. 10 to 0.15 is the practical limit, and this is based on the air/liquid flow rate ratio and spray liquid as shown in [Neya et al., Ship Engineering Research Institute Report 12-1 (S50.l) P, IJ]. For this reason, it was necessary to provide a flow rate control function on the gas side to achieve the desired turndown ratio during gas-only combustion under low combustion load.

Therefore, instrumentation equipment such as a flow rate control valve and a flow meter is required on the gas side, and an air-fuel ratio control system also requires a calculation device for calculating the required air amount according to the gas flow rate. Furthermore, when using natural gas-based city gas as the fuel gas and inexpensive C heavy oil as the fuel oil, it is economical to perform gas pressure atomization combustion using a spray combustor with a large flow rate ratio of the atomization medium. There were problems such as the inability to obtain desired effects.

The present invention provides an intermediate mixing type spray combustor in which the heat input ratio of gas, which is an atomization medium, is reduced to such an extent that a flow rate control device on the gas side at the time of a gas 4F cliff is not required.

The purpose is to easily realize a high turndown ratio at a low atomizing medium ratio without controlling the flow rate on the gas side.

Means for Solving Problems c] The present invention provides an injection hole that communicates an oil nozzle for supplying fuel oil and a gas nozzle for supplying fuel gas with a mixing nozzle, and injects fuel oil and fuel gas in a mixed state. In an intermediate mixing type gas pressure spray combustor formed at the tip of a mixing nozzle,
A primary mixing chamber is formed in the fuel oil and fuel gas mixing section, and the passage cross section from the primary mixing chamber to the mixing nozzle is narrowed.

[Operation] According to the present invention, the fuel oil passes through the oil nozzle, and the fuel gas for 1I formation passes through the gas nozzle, and are guided to the primary mixing chamber and mixed with each other. Furthermore, when the fuel oil and fuel gas are led from the primary mixing chamber to the mixing nozzle, the tendency of separation between the liquid flow and the air flow is reduced due to the effect of changing the direction of the streamlines and the stirring effect of the flow due to the narrowed passage cross section. The mixture is promoted by the mixing nozzle, and can be ejected from the ejection hole in a highly atomized state. This provides blast combustion air with a low heat input ratio of gas, which is an atomizing medium, to the extent that a flow rate control device on the gas side is not required during gas-only combustion, and the flow rate on the gas side can be controlled with a low atomizing medium ratio. It becomes possible to easily realize a high turndown ratio without the need for a high turndown ratio.

[Embodiment] FIG. 1 is a sectional view showing an intermediate mixing type gas pressure spray combustor according to an embodiment of the present invention.

The gas pressure spray combustor 10 includes an oil gun outer pipe 11 and an oil gun inner pipe 12, each of which has a double-pipe structure.
7 tomizers (burner chips) 13 are provided. That is, the 7 tomizer 13 includes the outer tube 11 and the atomizer 1.
It is connected to the outer tube 11 by a cap 14 that is screwed onto both of the tubes 3 and 3, and is directly screwed onto the inner tube 12. Here, a fuel oil supply passage 15 is provided between the outer pipe 11 and the inner pipe 12.
is formed, and a fuel gas supply passage 16 is formed in the inner tube 12.

The atomizer 13 includes an oil nozzle 17 that communicates with the fuel oil supply passage 15. A gas nozzle 1B communicating with the fuel gas supply passage 16, a primary mixing chamber 19, and a mixing nozzle 20 are formed. That is, the combustor 10 has one oil nozzle 17 that supplies fuel oil and one gas nozzle 18 that supplies fuel gas.
The mixture nozzle 20 is formed through a taper-shaped passage portion 22 (taper angle θ2) whose diameter is rapidly narrowed behind the mixing chamber 19, and an ejection hole through which fuel oil and fuel gas are ejected in a mixed state. 21 is formed at the tip of the mixing nozzle 20. The main gas nozzle 18, the primary mixing chamber 19, and the mixing nozzle 20 are formed in the axial center of the atomizer 13,
The oil nozzle 17 is 1 at a certain angle (incident angle θ1) with respect to the axis.
It communicates with the next mixing chamber 19.

Next, the operation of the above embodiment will be explained.

In the combustor 10, fuel oil passes through a fuel oil supply passage 15 and an oil nozzle 17 as shown by arrow A in FIG. 1, and fuel gas for atomization passes from a fuel gas supply passage 16 as shown by arrow B. The gases pass through gas nozzles 18 and are each introduced into a primary mixing chamber 19 where they are mixed with each other. Furthermore, mixing nozzle 2
When guided to 0, due to the changing direction of the streamline and the stirring effect of the flow due to the rapid narrowing of the passage cross section into a tapered shape,
In the conventional intermediate mixing type spray combustor shown in FIG. 2, the separation tendency of the liquid flow 31 and the air flow 32, which is relatively easy to occur, can be prevented, the mixing is promoted by the mixing nozzle 20, and the nozzle hole 21 is also It is said that it can be ejected in an atomized state. Note that the position where the primary mixing chamber 19 is squeezed into the mixing nozzle 20 must be located at the rear of the position where the oil nozzle 17 communicates with the primary mixing chamber 19, and the appropriate mixing chamber length governs the atomization performance. It is something to do. Thus, the fuel oil atomization performance of the intermediate-mix gas pressure atomization combustor according to the present invention can be better at a lower atomizing medium ratio than the conventional intermediate-mix gas pressure atomization combustor, without flow control on the gas side. A high turndown ratio can be achieved.

The intermediate mixing type gas pressure atomizing combustor 10 according to the above embodiment includes:
Combustor! 25X 10' kcal/) Ir cr) Applied to an industrial furnace burner. As shown in Table 1, the fuel oil used is C heavy oil, and the atomization medium is natural gas-based city gas.
3A was used. Gas pressure is 1.5kg/crn'G
The combustion load is changed by operating at a constant rate and adjusting the oil amount.

Furthermore, if we specify the specific dimensions of the combustor based on Fig. 3, the diameter 0 of the oil nozzle 17 is φ0.8tge, the diameter G of the gas nozzle 18 is φ1.5mm, and the diameter M1 of the primary mixing chamber 19 is φ0.8tge. $2.9mm, mixing nozzle 20 (7) diameter M2 is φ1
．． There are 8 proverbial layers. Also, the angle of incidence θ1 of the oil nozzle is eoI
As a result of investigating the atomization characteristics of various aperture shapes for the rear tapered passage section 22 of the zero-order primary mixing chamber 19, which is k, the main ones are shown in Table 2. It was found that the shape (tapered passage section 22) was optimal. Here, the taper angle θ2 of the tapered passage portion 22 is preferably 30 degrees to 60 degrees, and in the embodiment is θ2-50 degrees. Further, as shown in Table 3, the position where the oil is squeezed from the primary mixing chamber 19 to the mixing nozzle 20 and the oil nozzle 1
The relationship between 7 and the position communicating with the primary mixing chamber 19 governs the atomization to granulation characteristics, and in this example, 1 sentence = 5.
It was set as 2 m So.

The combustion load characteristics of this example are shown in Fig. 4.The turndown ratio is 1:
1O can be achieved continuously, ■Gas heat input ratio at rated combustion load -4.8%, ■Gas/liquid mass flow ratio W G / W L 0.043, ■Heat input ratio during gas-only combustion - 10.0% (
This is a significant improvement over the conventional spray combustor, which has a flame run ratio of 1:5 at a constant gas operating pressure. Furthermore, almost the entire combustion range is covered with low excess air combustion (02
= 1%) was achieved.

By using the gas pressure frost injection combustor according to the present invention in a burner for an industrial furnace, the following effects can be obtained.

■A high turndown ratio of about 1:10 can be obtained by controlling the gas operating pressure to a constant level or the oil-gas differential pressure to a constant level, which was previously necessary when high turndown performance was required. A side flow control device can be completely omitted.

(2) Since the heat input ratio of the gas which is the atomization medium can be lowered, when using inexpensive C heavy oil, the heat input ratio of the oil becomes relatively high, resulting in excellent economic effects.

[Effects of the Invention] As described above, the present invention provides an injection hole that connects an oil nozzle that supplies fuel oil and a gas nozzle that supplies fuel gas to a mixing nozzle and injects fuel oil and fuel gas in a mixed state. In an intermediate mixing type gas pressure spray combustor formed at the tip of a mixing nozzle, a primary mixing chamber is formed in the mixing part of fuel oil and fuel gas, and the passage cross section from the primary mixing chamber to the mixing nozzle is narrowed. This is how it was done. Therefore, we provide a spray combustor in which the heat input ratio of gas, which is an atomizing medium, is small enough to eliminate the need for a flow rate control device on the gas side during gas-only combustion. Easily realizing a high turndown ratio is an l1lf capability.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the intermediate mixing type gas pressure spray combustor of the present invention, FIG. 2 is a schematic diagram showing the gas-liquid flow in a conventional intermediate mixing type gas pressure spray combustor, and FIG. The figure shows the related dimensions of the intermediate mix type gas pressure spray combustor, Figure 4 shows the combustion load characteristics of an industrial furnace burner using the intermediate mix type gas pressure spray combustor of the present invention, and Figure 5 shows the conventional FIG. 2 is a schematic diagram of a spray combustor. lO...Gas pressure frost combustor, 17...Oil nozzle. 18... Gas nozzle, 19... Primary mixing chamber, 20...
...Mixing nozzle, 21...Blowout hole. Agent Patent Attorney Osamu Shiokawa 1 Figure 2 Figure 3 Figure eM-30~60fi Figure 4 Imaginary Load (X)

Claims (1)

[Claims] (1) An intermediate area formed by communicating an oil nozzle that supplies fuel oil and a gas nozzle that supplies fuel gas with a mixing nozzle, and forming an injection hole at the tip of the mixing nozzle that ejects fuel oil and fuel gas in a mixed state. A gas pressure spray combustor of mixed type, characterized in that a primary mixing chamber is formed in a mixing section of fuel oil and fuel gas, and a passage cross section from the primary mixing chamber to a mixing nozzle is narrowed.