JPS6339546Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a premixed gas burner for high-load combustion, in particular, fuel gas is ejected as a swirling flow into a cup-shaped flame stabilizer, and primary air is supplied from the center of the flame stabilizer and mixed therewith. Secondary air is divided by a cup-shaped flame stabilizer for primary mixing, and the secondary air is further mixed for secondary mixing to achieve a blue flame and high-load combustion in the combustion tube, and also has a cooling effect on the primary air. suppresses the decomposition of fuel gas and
Good combustion performance can be achieved even by reducing the combustion amount of high-calorie fuel gas with a slow combustion rate to about 1/20, and the occurrence of carbon troubles caused by carbon accumulation in the nozzle area can be minimized. ,
In addition, the cooling effect of the secondary air prevents damage to the combustion tube, etc., and the combustion tube is compact and has excellent spalling resistance (resistant to rapid heating and cooling).
To provide a premixed gas burner that can be made lightweight.

In conventional pre-mix burners, when using a high-calorie fuel gas with a slow combustion rate such as LPG gas, turning down the combustion amount to about 1/3 will ensure sufficient mixing of the gas and air. As a result, the combustion condition deteriorates and the burner loses its original function.

In addition, recently, preheated air (300°C to 500°C) is used for combustion air to save energy, but when using high-calorie gas, free carbon is likely to be generated due to direct contact with the preheated air. The heat of the preheated air decomposes the fuel gas before combustion, causing carbon to accumulate in the nozzle, causing incomplete combustion. Furthermore, the fired refractories and castable refractories that make up the combustion chamber of conventional burners are heavy and bulky, and have the disadvantage of being damaged by expansion and contraction due to rapid heating and cooling.

This idea was made in order to eliminate the above-mentioned drawbacks of the conventional method.The primary air passage and the fuel gas passage were formed on the proximal end side of the burner body, which was equipped with a long combustion tube and had a secondary air passage formed therein. The burner head is fixed, and a fuel gas pipe is connected to the fuel gas passage of the burner head through the secondary air passage of the burner body, and at its tip, a number of secondary air holes are bored in the peripheral wall, and between it and the combustion cylinder. A cup-shaped flame stabilizer having a secondary air flow passage and a dam plate is fixedly installed, and a primary air pipe is connected to the primary air passage through the fuel gas passage and the fuel gas pipe, and its tip is secured. A gas nozzle that protrudes into the flame chamber and generates a swirling flow is provided at the tip of the fuel gas pipe, and an ignition plug is provided near the gas nozzle. The secondary air is blown out and supplied inward for primary mixing to form a circulating flow and combustion, and the secondary air that is divided into the mixed gas is passed over the weir plate of the flame stabilizer and mixed for a secondary purpose. The cooling effect of the primary air suppresses the decomposition of fuel gas to prevent carbon troubles, and the cooling effect of the secondary air increases combustion. This invention relates to the invention of a pre-mixed gas burner that prevents damage to the tube, etc., has a combustion tube made of silicon nitride-bonded silicon carbide, etc. with good thermal conductivity, has spalling resistance, and can be made compact.

An embodiment of this invention will be described below based on the drawings.

In Fig. 1, reference numeral 1 denotes a long combustion tube made of silicon nitride-bonded silicon carbide or the like with good thermal conductivity, which is fitted with a ceramic fiber packing at one end of the burner body 3 which forms a secondary air passage 2. etc., and fix it with screws 20. 2a is a secondary air supply port of the secondary air passage. The combustion tube has excellent spalling resistance, so it can be made thin and lightweight, and a straight cylindrical body is used in the example, but the combustion tube is not limited to this, and can be changed depending on the furnace body. You are free to use a narrowed or enlarged tip.

A burner head 6 having a primary air passage 4 and a fuel gas passage 5 is fixed to the other end of the burner body 3. 4a is the primary air supply port of the primary air passage; 5
a is the supply port of the fuel gas passage.

The fuel gas pipe 7 is the secondary air passage 2 of the burner body 3
The fuel gas passage 5 of the burner head 6 passes through the
A cup-shaped flame stabilizer 11 is fixedly connected to the fuel gas pipe 7 and at the tip of the fuel gas pipe 7. As shown in FIGS. 1 and 3, the cup-shaped flame stabilizer 11 is provided with several rows of secondary air holes 8 near the tip of its peripheral surface, and a secondary air hole 8 is provided between the outer periphery of the tip and the combustion tube 1. A weir plate 10 is formed with a gap or secondary air flow passage 9 through which air passes, and the secondary air from the secondary air passage 2 of the burner body enters the mixing chamber through the secondary air hole 8; The air is divided into those passing through the outer peripheral secondary airflow passage 9. The ratio of this divided flow is, for example, 6:4, 5:5, etc. between the amount flowing inward and the amount passing through the outer periphery. Although the weir plate 10 at the tip of the cup-shaped flame stabilizer 11 is annular in the embodiment, it is not limited to this, but may have an appropriate shape, such as an uneven shape, to increase or decrease the flow rate passing through the secondary airflow passage 9.

Further, the primary air pipe 12 is inserted into the center of the fuel gas passage 5 and the fuel gas pipe 7, and is inserted into the primary air passage 4.
The primary air pipe 12 is connected to the flame stabilizer 11 so that the tip of the primary air pipe 12 slightly protrudes into the flame stabilizer 11. Furthermore, a gas nozzle 13 is provided at the tip of the fuel gas pipe 7 to generate a swirling flow between the gas nozzle 13 and the outer peripheral surface of the primary air pipe 12.
As shown in FIG. 2, the gas nozzle 13 is provided with several gas ejection slits 14 radially disposed at arbitrary angles with respect to the center so as to produce a swirling flow in the ejected gas. In addition, 15 is an ignition plug provided near the gas nozzle, 16 is a sight hole, 17 is a flame detector provided at the rear end of the primary air passage 4, 18 is a fixing ring, and 19 is glued to the outer periphery of the combustion tube 1. This is an auxiliary burner tile made of ceramic fiber.

Since this device has the above-mentioned configuration, secondary combustion air is divided into an inward flow and a flow passing around the outer circumference by a cup-shaped flame stabilizer, and swirling air flows from a gas nozzle in the mixing chamber inside the flame stabilizer. Primary air is supplied from the primary air pipe to the fuel gas entering the fuel gas to mix and dilute it, and secondary air that enters from the secondary air hole in the peripheral wall of the flame holder is flowed into the fuel gas for primary mixing, ignition and combustion, and then This mixed gas is subjected to secondary mixing by increasing the speed of secondary air passing through the secondary air flow passage on the outer periphery of the flame stabilizer using a weir in the combustion tube, and blue flame combustion occurs in the long combustion tube.

In other words, the flame stabilizing mechanism is such that a recirculation area is formed by the air-fuel mixture in the long combustion tube at the front beyond the weir plate of the cup-shaped flame stabilizer. A stable mixed turbulent flow is formed between the gas mixture, which is a primary mixture of primary air and secondary air, and the secondary air separated from the secondary air flow passage, and combustion is performed as a stable flame that does not blow out.
Further, the primary air cools the fuel gas when passing through the primary air pipe, and the secondary air also cools the fuel gas by flowing along the combustion tube.

According to this invention described above, primary air is ejected into the swirling fuel gas in the flame stabilizer to mix and dilute it, and secondary air is supplied to it to perform primary mixing.
The secondary air divided into this mixed gas is supplied at increased speed over the weir of the flame stabilizer to perform secondary mixing, improving the mixing of air and fuel gas and recirculating it within the long combustion cylinder. Blue flame and high-load combustion can be achieved by forming a region. As a result, LPG gas with a high calorific value and a slow combustion rate can be completely burned under high load at the stoichiometric air ratio, and the turndown ratio is extremely large at 1:20 compared to the general turndown ratio of 1:5. You can take it. In addition, as shown in Figure 4, the combustion range is good even when the amount of air is less than the theoretical amount, and cyclic combustion is also possible.When used in a heating furnace, etc., the temperature can be easily and accurately controlled, and a premix burner can be used. Because of this, there is no backfire even during low combustion, making it safe to use, and preheated air can be used as secondary air, saving energy. Also, since primary air is introduced,
Blue flame combustion without yellow flame is possible even with LPG gas, etc., which prevents carbon adhesion and accumulation on the nozzle, etc., and allows maintenance-free use for long periods of time.

Furthermore, when preheated air is used as secondary air,
The fuel gas and primary air are mixed and diluted in the flame holder before coming into contact with the secondary air, which is preheated air, and the secondary air is mixed with it to perform the primary mixing, so free carbon is generated in the gas nozzle and flame holder. In addition, even if this preheated air is used to cause decomposition of the fuel gas flowing inside the fuel gas pipe, since the primary air pipe is inserted into the fuel gas pipe, the cooling effect of the primary air will prevent the fuel gas from decomposing. In the case of high-calorie gases such as LPG gas, it is possible to minimize the occurrence of carbon troubles that tend to occur at low inputs, and at the same time, the flame detector It can also prevent overheating.

In addition, the cooling effect of secondary air can cool the red-hot combustion tube, so the combustion tube is attached to the burner body with a ceramic fiber packing to prevent overheating of the joints secured with numerous screws and the burner body. This prevents damage to the combustion tube, and the combustion tube can be easily attached and removed, making it convenient for replacement.

Furthermore, if the combustion tube is made of silicon nitride-bonded silicon carbide, which has good thermal conductivity, it has spalling resistance, so the combustion tube can be made thinner, making it lighter and more compact, which makes assembly easier. Since the burner itself is compact and lightweight, it can be easily installed in a heating furnace, etc., and has many practical benefits.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional view showing the pre-mixing type gas burner of this invention, Figure 2 is a side view of the same, Figure 3 is a partially cutaway front view of the cup-shaped flame holder, and Figure 4 is the gas burner of this invention. It is a graph showing a combustion range. DESCRIPTION OF SYMBOLS 1... Combustion tube, 2... Secondary air passage, 3... Burner body, 4... Primary air passage, 5... Fuel gas passage, 6... Burner head, 7... Fuel gas pipe,
8...Secondary air hole, 9...Secondary air flow path, 10
... Weir plate, 11 ... Cup-shaped flame holder, 12 ... Primary air pipe, 13 ... Gas nozzle.

Claims (1)

[Scope of utility model registration request] A burner head 6 having a primary air passage 4 and a fuel gas passage 5 is fixed to the base end of a burner body 3 which is equipped with a long combustion tube 1 and has a secondary air passage 2 formed therein. A fuel gas pipe 7 is connected to the fuel gas passage 5 of the burner head 6 through the air passage 2.
A plurality of secondary air holes 8 are bored in the peripheral wall at the tip of the fuel gas pipe 7, and a secondary air flow passage 9 is provided between the front end and the combustion cylinder 1, and the weir plate 1 is connected to the fuel gas pipe 7.
A cup-shaped flame stabilizer 11 provided with The tip of the air pipe 12 projects into the flame stabilizer 11 in the axial direction, and a gas nozzle 13 is provided at the tip of the fuel gas pipe 7 with the slit 14 displaced at an arbitrary angle from the center. A spark plug 15 is provided near the gas nozzle, and primary mixing is performed by supplying primary air in the axial direction from the primary air pipe and inward through the air hole 8 of the flame stabilizer to the swirling flow of gas generated from the gas nozzle. Then, in the combustion tube 1, the weir plate 1
A pre-mixing type gas burner characterized in that a part of secondary air is supplied through a secondary air flow path 9 of 0 to perform secondary mixing and combustion.