TWI793459B - Method for adjusting the flame of pilot burner - Google Patents

Abstract

A method for adjusting the flame of pilot burner is provided. The method for adjusting the flame of pilot burner comprises providing an air into a pilot burner at a certain air pressure; providing a combustible gas into the pilot burner at a combustible gas pressure, and the air and the combustible gas are mixed to form mixed gas; applying a high voltage arc at one end of the pilot burner; increasing the combustible gas pressure until the mixed gas is ignited by the high-pressure arc to form a flame, thereby obtaining a lower limit of combustible gas ignited pressure; and increasing the combustible gas pressure until the flame is extinguished, thereby obtaining an upper limit of combustible gas ignited pressure; wherein an ignitable interval is defined between the lower limit of combustible gas ignited pressure and the upper limit of combustible gas ignited pressure.

Description

How to adjust the flame of the pilot burner

The invention relates to an adjustment method, in particular to an adjustment method for a pilot burner flame.

In the heating system in the steelmaking industry, such as the heating system of the annealing furnace in the galvanizing production line, the steel strip is heated mainly by the mechanism of heat radiation and heat convection, so that the steel strip reaches the required annealing temperature. Such a heating system includes a burner (Burner) and a pilot burner (Pilot Burner). The function of the pilot burner is to pre-mix air and combustible gas into a mixed gas, and ignite the gas in the mixer with a high-voltage arc to form a flame, then feed in the main fuel and use the flame of the pilot burner to ignite the main fuel. Thereby, the unignited main fuel is prevented from entering the burner, thereby reducing the explosion hazard caused by the accumulation of unignited main fuel in the burner.

However, the above-mentioned heating system in the steelmaking industry is quite large, resulting in a large number of pilot burner pipelines, and the pilot burner itself has the problem of not being able to generate a flame, and thus cannot ignite the main fuel, which will also cause the above-mentioned problem of accumulation of the main fuel . Therefore, in the current production line, an excessive amount of combustible gas is often passed into the pilot burner to ensure that the pilot burner can definitely generate flames.

However, an excessive amount of combustible gas will produce a burning yellow flame, which means that the combustible gas cannot be completely combusted, making the flame stability worse, which in turn affects the heating efficiency. In addition, because the combustible gas cannot be completely burned, the incompletely combusted combustible gas will accumulate in the burner and pilot burner, which will cause unexpected reactions to the burner and pilot burner, such as unexpected knocking, which are It can directly affect the operation or service life of the burner and pilot burner. Finally, the current method needs to consume an excessive amount of combustible gas, thus further increasing the production cost.

Therefore, it is necessary to provide a method for adjusting the flame of the pilot burner to solve the problems existing in the conventional technology.

The purpose of the present invention is to provide a pilot burner flame adjustment method to avoid the problem of main fuel accumulation, and can provide the ignitable range and ignitable range of combustible gas. In this way, the ignition parameters of the pilot burner flame can be optimized, and the stability of the pilot burner flame is increased, thereby reducing the consumption of combustible gas. In addition, when the furnace is cold, the problem that the flame of the pilot burner is not easy to ignite is also significantly improved.

In order to achieve the above object, the present invention provides a method for adjusting the flame of a pilot burner, comprising: supplying air into a pilot burner with a selected air pressure; supplying combustible gas to the pilot burner with a combustible gas pressure Inside, and the air and the combustible gas form a mixed gas; apply a high-voltage arc at one end of the pilot burner; increase the pressure of the combustible gas until the mixed gas is ignited by the high-voltage arc to form a flame, and then obtain a combustible gas that can be ignited and increase the pressure of the combustible gas until the flame is extinguished, thereby obtaining an upper limit of the ignitable pressure of the combustible gas; wherein the lower limit of the ignitable pressure of the combustible gas and the upper limit of the ignitable pressure of the combustible gas form a Ignition range.

In an embodiment of the present invention, the method for adjusting the flame of the pilot burner further includes: adjusting the selected air pressure multiple times; obtaining multiple lower limit values of the combustible gas ignitable pressure corresponding to the selected air pressure, A plurality of the ignitable pressure upper limit of the combustible gas and a plurality of the ignitable intervals; and a plurality of the ignitable intervals are collected to form an ignitable range.

In an embodiment of the present invention, the multiple adjustments of the selected air pressure include: increasing the selected air pressure by 100mmwc.

In an embodiment of the present invention, the method for adjusting the flame of the pilot burner further includes: selecting a required combustible gas pressure value and a required air pressure value corresponding to the required combustible gas pressure within the ignitable range , as an operating point.

In an embodiment of the present invention, the required air pressure value at the operating point is between 100 and 450 mmwc.

In an embodiment of the present invention, the required combustible gas pressure value at the operating point is between 100 and 450 mmwc.

In an embodiment of the present invention, the method for adjusting the flame of the pilot burner further includes: using a flame sensor to determine whether the flame is formed or extinguished, wherein when a photoelectric signal of the flame sensor is greater than 1mA, it is determined The flame is formed, and the flame is judged to be extinguished when the photoelectric signal is less than 1mA.

In an embodiment of the present invention, the method for adjusting the flame of the pilot burner further includes: confirming whether the flame will be extinguished within 1 to 10 seconds.

In an embodiment of the present invention, the pressure of the combustible gas is between 50 and 500 mmwc.

In an embodiment of the invention, the selected air pressure is between 50 and 500 mmwc.

As mentioned above, the pilot burner flame adjustment method provided by the present invention can not only reduce the explosion hazard caused by the accumulation of unignited main fuel in the burner, but also provide the ignitable range and ignitable range of combustible gas. Through the ignitable interval and ignitable range, the stability of the pilot burner flame can be increased, thereby reducing the consumption of combustible gas.

In order to make the above and other objects, features, and advantages of the present invention more comprehensible, preferred embodiments of the present invention will be exemplified below in detail together with the attached drawings. Furthermore, the directional terms mentioned in the present invention are, for example, up, down, top, bottom, front, back, left, right, inside, outside, side, surrounding, central, horizontal, transverse, vertical, longitudinal, axial, The radial direction, the uppermost layer or the lowermost layer, etc. are only directions referring to the attached drawings. Therefore, the directional terms used are used to illustrate and understand the present invention, but not to limit the present invention.

Please refer to Fig. 1, Fig. 1 is a schematic structural view of an existing pilot burner. A pilot burner 100 includes an air supplier 110 , a combustible gas supplier 120 , a high voltage electric ignition coil 130 and a flame sensor 150 . The air supplier 110 is used to supply air Air into the pilot burner 100 at a selected air pressure. The combustible gas supplier 120 is used to supply combustible gas NG into the pilot burner 100 at a combustible gas pressure. Accordingly, the air Air and the combustible gas NG can form a mixed gas in the pilot burner 100 . The high voltage electric ignition coil 130 can apply a high voltage arc at one end of the pilot burner 100 to ignite the gas mixture to form a flame 140 . The flame sensor 150 can be disposed at the other end of the pilot burner 100 , and the flame sensor 150 is used to detect the flame 140 . The flame sensor 150 can use a photoelectric signal to determine whether the flame 140 is formed, for example, when the photoelectric signal is greater than 1 mA, it is determined that the flame 140 is formed, and when the photoelectric signal is less than 1 mA, it is determined that the flame 140 is extinguished or not formed.

However, the formation of the flame 140 is affected by the ratio of air to combustible gas. Please refer to Figure 2, which is a screenshot of the pilot burner flame. FIG. 2 is a screenshot of the image of the flame 140 formed when the selected air pressure is 100 mmwc and different combustible gas pressures P _NG are provided. When the pressure P _NG of the combustible gas reaches 120mmwc, the mixed gas will be ignited to form the flame 140 . As the combustible gas pressure P _NG increases, the length of the flame 140 also increases. For example, when the combustible gas pressure P _NG increases to 240mmwc, the flame 140 has good stability and is not easy to extinguish or shake. And when the combustible gas pressure P _NG increases to 270 mmwc, the flame 140 forms a double-layer flame structure with a blue flame 141 and a red flame 143 . At this time, the air is slightly insufficient, and the mixed gas cannot be completely combusted, so the red flame 143 is formed at the end of the flame 140 . When the combustible gas pressure P _NG increases to 300mmwc to 250mmwc, the air in the pilot burner is obviously insufficient, and the flame 140 is at the tail end of the flame 140 in addition to the blue flame 141 and the red flame 143 A yellow flame 145 is formed. At this time, the flame 140 is still stable and will not go out, but the consumption of the combustible gas is too large.

Therefore, the present invention provides a method for adjusting the flame of the pilot burner, which can reduce the explosion hazard caused by the accumulation of unignited main fuel in the burner, and can also provide the ignitable range and ignitable range of the combustible gas, thereby reducing the combustible gas. gas usage. For the embodiments of the adjustment method of the pilot burner flame, please refer to Fig. 3 to Fig. 5 . Fig. 3 is a step-by-step flow chart of a pilot burner flame adjustment method according to an embodiment of the present invention. Fig. 4 is a flow chart of another step of a pilot burner flame adjustment method according to an embodiment of the present invention. FIG. 5 is a flow chart of step S150 in the embodiment of the present invention.

As shown in Figures 3 to 5, the method for adjusting the flame of the pilot burner includes the following steps:

In step S110, air is supplied to a pilot burner at a selected air pressure. And the selected air pressure can be between 50 and 500 mmwc.

In step S120, a combustible gas is supplied into the pilot burner at a combustible gas pressure, and the air and the combustible gas form a mixed gas. And the combustible gas pressure is between 50 and 500mmwc. It should be understood that the combustible gas may be methane, ethane, propane or other combustible gases, or a combination of combustible gases (eg, natural gas).

Step S130, applying a high voltage arc at one end of the pilot burner.

Step S140, increasing the pressure of the combustible gas until the mixed gas is ignited by the high-voltage arc to form a flame, and then a lower limit value of the ignitable pressure of the combustible gas is obtained.

Step S150, increasing the pressure of the combustible gas until the flame is extinguished, and then obtaining an upper limit of the ignitable pressure of the combustible gas; wherein the lower limit of the ignitable pressure of the combustible gas and the upper limit of the ignitable pressure of the combustible gas form an ignitable interval . In step S150, it is also possible to determine whether the flame is formed or extinguished through steps S151 and S152. In step S151, a flame sensor is used to determine whether the flame is formed or extinguished. When the photoelectric signal is greater than 1mA, it is determined that the flame is formed; when the photoelectric signal is less than 1mA, it is determined that the flame is extinguished. In step S152, it is determined whether the flame will be extinguished within 1 to 10 seconds.

The method for adjusting the flame of the pilot burner further includes: step S160, adjusting the selected air pressure multiple times; for example, increasing the selected air pressure by 100mmwc.

Step S170, obtaining multiple lower limit values of the ignitable gas pressure, multiple upper limit values of the ignitable pressure of the combustible gas and multiple ignitable intervals corresponding to the selected air pressure.

Step S180, collecting a plurality of the ignitable intervals to form an ignitable range.

Step S190, selecting a required combustible gas pressure value and a required air pressure value corresponding to the required combustible gas pressure within the ignitable range as an operating point. The desired air pressure value for the operating point is between 100 and 450 mmwc. The required combustible gas pressure value at the operating point is between 100 and 450 mmwc.

Please refer to Figure 6. Figure 6 shows the ignitable range and ignitable range of the pilot burner under various air pressures. Figure 6 is an example of the method for adjusting the flame of the pilot burner provided by the present invention, wherein ˜ is the lower limit of the ignitable pressure of the combustible gas, ¢ is the ignitable pressure value of the combustible gas when forming a double-layer flame structure, ▲ is the ignitable pressure value of the combustible gas when forming a yellow flame, and Ü is the upper limit value of the ignitable pressure of the combustible gas. According to Figure 6, the air pressure of the original ignition operation point 301 of the annealing furnace in the existing production line is 450mmwc, and the combustible gas pressure is 350mmwc, which can be reduced to the current ignition operation point 303. The force is 100 to 120mmwc. In this way, the consumption of combustible gas can be reduced from 55.4Nm ³ /h to 34.6Nm ³ /h, a reduction of 37%.

As mentioned above, the pilot burner flame adjustment method provided by the present invention can not only reduce the explosion hazard caused by the accumulation of unignited main fuel in the burner, but also provide the ignitable range and ignitable range of combustible gas. Through the ignitable interval and ignitable range, the stability of the pilot burner flame can be increased, thereby reducing the consumption of combustible gas.

Although the present invention has been disclosed with preferred embodiments, it is not intended to limit the present invention. Anyone skilled in this art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection shall be determined by the scope of the attached patent application.

100: pilot burner 110: Air supplier 120: combustible gas supplier 130: High voltage electric fire coil 140: Flame 141: blue flame 143: red flame 145: yellow flame 150: flame sensor 301: Original ignition operating point 303: Current ignition operating point Air: air NG: combustible gas S110～S190: Steps

Fig. 1 is a schematic structural view of the current pilot burner structure. Figure 2 is a screenshot of an image of the pilot burner flame. Fig. 3 is a step-by-step flow chart of a pilot burner flame adjustment method according to an embodiment of the present invention. Fig. 4 is a flow chart of another step of a pilot burner flame adjustment method according to an embodiment of the present invention. FIG. 5 is a flow chart of step S150 in the embodiment of the present invention. Figure 6 shows the ignitable interval and ignitable range of the pilot burner under various air pressures.

S110~S150: steps

Claims (8)

A method for adjusting the flame of a pilot burner, comprising: supplying air into a pilot burner with a selected air pressure; supplying combustible gas into the pilot burner with a combustible gas pressure, and the air and the combustible gas Form a mixed gas; apply a high-voltage arc at one end of the pilot burner; increase the pressure of the combustible gas until the mixed gas is ignited by the high-voltage arc to form a flame, and then obtain a lower limit of the ignitable pressure of the combustible gas; increase the pressure of the combustible gas until the flame is extinguished, and then obtain an upper limit of the ignitable pressure of the combustible gas; wherein the lower limit of the ignitable pressure of the combustible gas and the upper limit of the ignitable pressure of the combustible gas form an ignitable interval, wherein the pressure of the combustible gas is within Between 50 and 500mmwc; adjust the selected air pressure multiple times; obtain a plurality of lower limit values of the ignitable pressure of the combustible gas, a plurality of upper limits of the ignitable pressure of the combustible gas and a plurality of the ignitable pressure of the selected air pressure an ignitable interval; and collecting a plurality of the ignitable intervals to form an ignitable range. The method for adjusting the pilot burner flame according to claim 1, wherein the multiple adjustments to the selected air pressure include: increasing the selected air pressure by 100mmwc. The method for adjusting the flame of the pilot burner as described in claim 1 further includes: selecting a required combustible gas pressure value and a required air pressure value corresponding to the required combustible gas pressure within the ignitable range as a operating point. The method for adjusting the flame of the pilot burner according to claim 3, wherein the required air pressure value at the operating point is between 100 and 450 mmwc. The method for adjusting the flame of the pilot burner according to claim 5, wherein the required combustible gas pressure value at the operating point is between 100 and 450mmwc. The method for adjusting the flame of the pilot burner as described in Claim 1 further includes: using a flame sensor to determine whether the flame is formed or extinguished, wherein when a photoelectric signal of the flame sensor is greater than 1mA, it is determined that the flame is formed , when the photoelectric signal is less than 1mA, it is judged that the flame is extinguished. The method for adjusting the flame of the pilot burner as described in Claim 6 further includes: confirming whether the flame will be extinguished within 1 to 10 seconds. The method for adjusting the flame of the pilot burner as described in Claim 1, wherein the selected air pressure is between 50 and 500mmwc.

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