JPH0445725B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a gas combustion burner installed in a heat exchanger tube or the like that transmits heat to the outside.

(Prior art) Conventionally, gas burners that are installed at the base end of heat transfer tubes that are immersed in frying oil to transfer heat, and that use city gas, household gas, or other gases, are either ventilate type or blown type. Burners were used, and these burners ejected gas directly toward atmospheric pressure through small holes.

(Problem to be solved by the invention) However, the pressure of city gas, household gas, and other gases used in these gas combustion burners is only several hundred millimeters higher in water column pressure than atmospheric pressure, and the fumarole When the water exits the hole, the pressure is reduced to a few millimeters of water, and the mixture ratio of air and fuel gas reaches several times the amount of air required, so the flame temperature becomes lower than the theoretical flame temperature. Moreover, there was a problem of poor combustion efficiency.

In addition, in the case of a Bunsen burner, which mixes air midway and ignites the mixed gas at the burner hole, for example, it is difficult to maintain a proper mixing ratio of fuel gas and primary air for combustion, and Air burns at a freer rate than the atmosphere. Furthermore, in such burners, the gas pressure has lost most of its initial pressure energy, and combustion takes place at atmospheric pressure, again with very low flame temperatures. For this reason, methods have been taken to supply fuel gas to the combustion chamber by separately providing an air pressure feeding device or a suction device, but these devices are complicated and expensive, and they are difficult to handle. It was hot.

The present invention has been made in view of such conventional problems, and it is possible to effectively retain gas source pressure energy even at the combustion start point without providing an expensive air supply means, and to improve the mixing ratio with air. The purpose of this invention is to provide a gas combustion burner with a simple structure that allows for optimal self-control.

(Means for Solving the Problems) The gist of the present invention for achieving the above object is that a constriction part of a predetermined diameter is provided at a gas outlet of a combustion gas supply pipe and connected to the gas outlet. and a fuel gas injection nozzle having a pressure recovery part that is flared toward the end and connected to the constriction part; A primary mixing nozzle having a pressure recovery part that is connected to the constriction part and has a shape that widens toward the end, and a constriction protrusion provided at the tip of the pressure recovery part, and is arranged concentrically with the fuel gas injection nozzle and the primary mixing nozzle. The secondary mixing nozzle has an air intake port on the proximal end side and a mixed gas ejection port of a predetermined diameter on the distal end side, and the secondary mixing nozzle has a A gas combustion burner is characterized in that a secondary air flow passage is formed around the outer periphery of a primary mixing nozzle.

(Function) According to this gas combustion burner, the energy possessed by the source gas of the fuel is converted into gas velocity dynamic pressure by the fuel gas injection nozzle, and this gas velocity dynamic pressure is used to direct the primary air for combustion from the primary air intake port. is introduced into the constricted portion of the primary mixing nozzle, and a primary mixed gas is formed in the constricted portion. Since this throttle part has a predetermined diameter, the amount of primary air introduced is appropriately limited, and therefore the primary mixed gas has a stoichiometric mixing ratio or less.

A part of the velocity energy of the primary mixed gas that has passed through the constriction part is gradually converted into pressure energy in the pressure recovery part of the primary mixing nozzle which is flared toward the end, and the pressure is recovered. In this pressure recovery section, the fuel gas recovers most of its original pressure.

Next, the primary mixed gas that has passed through the pressure recovery section has a flame propagation velocity higher than the flame propagation velocity also at the throttle protrusion of the primary mixing nozzle. The primary mixed gas ejected from the primary mixing nozzle becomes high-velocity again, and the pressure becomes lower than the jet pressure. Secondary air for combustion is introduced from the secondary air flow passage to the mixed gas jetting section of the secondary mixing nozzle. will be sent to Since the diameter of the mixed gas jetting part is also formed to a predetermined size,
The mixing ratio between the amount of secondary air and the primary mixed gas is theoretically optimal. Further, the secondary mixed gas mixed in the mixed gas jetting section still has a flow velocity higher than the flame propagation velocity, so it does not burn.

Then, the secondary mixed gas ejected from the secondary mixing nozzle slows down to a flow velocity sufficient for ignition and flame preservation, for example, in a heat transfer tube into which the tip of the secondary mixing nozzle is inserted, and ignites in the heat transfer tube. It will be done.

(Example) Next, an example of the present invention will be described in detail based on the drawings.

A in the figure is a gas combustion burner, and the gas combustion burner A is composed of a plurality of element members arranged coaxially, and the fuel gas is connected to the gas jet port 11 of the fuel gas supply pipe 10. Spout nozzle 20
, an ejector-type primary mixing nozzle 40 that is disposed on the outer periphery of the tip of the fuel gas injection nozzle 20 via the primary air intake port 30 and mixes the fuel gas and primary air to send out a primary mixed gas; A secondary airflow passage 50 is formed on the outer periphery of the primary mixing nozzle 40 and an ejector-shaped secondary mixing nozzle 60 is arranged concentrically to send out the secondary mixed gas. The tip of the nozzle 60 is a heat transfer tube 70
is inserted into.

A gas jet port 11 is formed in the fuel gas supply pipe 10 . Note that a large number of gas jet ports 11 are arranged in the fuel gas supply pipe 10 at predetermined intervals or irregularly.

As shown in FIGS. 2 and 3, the fuel gas jetting nozzle 20 has a base end joined to the edge of the gas jetting port 11, and has a throttle of a predetermined diameter connected to the gas jetting port 11. 21, and a pressure recovery portion 22 which is connected to the constricted portion 21 and has a shape that widens toward the end. The length l ₁ and diameter d ₁ of the constriction part 21 are:
It is an important factor that determines the fuel gas injection pressure. Further, the divergence angle 〓 ₁ and the length L ₁ of the pressure recovery section 22 are used to convert the velocity energy of the fuel gas flowing out through the constriction section 21 into pressure energy.

On the other hand, the outer periphery of the tip of the fuel gas injection nozzle 20 is formed into a gentle conical shape, and a primary air intake port 30 is formed at a predetermined interval on the outer periphery of the tip. A mixing nozzle 40 is provided.

As shown in FIGS. 1 and 4, a constriction portion 41 of a predetermined diameter is formed at the base end of the primary mixing nozzle 40 to limit the amount of primary air through the primary air intake port 30. . The length l ₂ and the diameter d ₂ of the constricted portion 41 are important factors that limit the amount of primary air and ultimately determine the primary mixing ratio with the fuel gas. A pressure recovery section 42 having a shape that widens toward the end is connected to the tip of the constricted section 41 . The divergence angle 〓 ₂ and the length L ₂ of the pressure recovery section 42 are used to convert the velocity energy of the primary mixed gas flowing out through the constriction section 41 into pressure energy. A constriction protrusion 43 is formed at the tip of the pressure recovery section 42 . Diameter of the aperture protrusion 43
d ₃ is an important factor that determines the ejection pressure of the primary mixed gas that passes through the pressure recovery section 42 and flows out.

A secondary mixing nozzle 60 is disposed concentrically around the outer periphery of the fuel gas injection nozzle 20 and the primary mixing nozzle 40 so as to form an airflow passage. The base end of the secondary mixing nozzle 60 is cut out at multiple locations at intervals in the circumferential direction to form air intake ports 6.
1 is formed and connected to the fuel gas supply pipe 10. The air flow passage formed on the outer periphery of the fuel gas injection nozzle 20 becomes the primary air flow passage 44, and primary air for combustion is mixed through the air intake 61, the primary air flow passage 44, and the primary air intake 30. It is introduced into the constriction section 41 of the nozzle 40.

The air flow passage formed around the outer periphery of the primary mixing nozzle 40 serves as a secondary air flow passage 50. The primary mixing nozzle 40 is supported by a plurality of supports 62 provided with secondary air passages secured in the inner circumference of the secondary mixing nozzle 60.
They are arranged concentrically within 0.

On the other hand, a mixed gas jetting part 63 having a predetermined diameter is formed at the tip of the secondary mixing nozzle 60 . The diameter d ₄ and the length l ₄ of the mixed gas jetting part 63 determine the mixing ratio between the secondary air passing through the secondary air flow passage 50 from the air exchange port 61 and the primary mixed gas flowing out from the primary mixing nozzle 40. is an important factor in determining
Further, the secondary mixed gas to be mixed is set to be higher than the flame propagation velocity.

The tip of the secondary mixing nozzle 60 is connected to the heat transfer tube 7.
It is inserted into 0.

Next, the operation of the gas combustion burner constructed in this way will be explained.

A fuel source (not shown) is connected to the base end of the fuel gas supply pipe 10 to supply fuel. This fuel is generally city gas or similar gas,
The supply pressure is several hundred millimeters of water column pressure higher than atmospheric pressure.

First, the energy possessed by the fuel gas ejected from the gas ejection port 11 of the fuel gas supply pipe 10 is transferred to the fuel gas ejection nozzle 20 connected to the gas ejection port 11.
The gas velocity is converted into dynamic pressure by the throttle section 21 and the pressure recovery section 22.

As a result, the fuel gas ejected from the ejection port of the fuel gas ejection nozzle 20 can obtain a high ejection speed,
Primary air is introduced from the primary air intake port 30 at this jetting speed. The intake amount of the primary air is controlled by the aperture d ₂ of the constriction portion 41 of the primary mixing nozzle 40 . The primary air and fuel gas become a primary mixed gas while passing through the throttle section 41 and the pressure recovery section 4
2.

In the pressure recovery section 42, the velocity energy in the constriction section 41 is gradually recovered, and if the angle = ₁ is the required angle and the length _L2 is the required length for the diameter _d2 , the pressure near the pressure before the fuel gas is ejected is The divergence angle 〓 ₂ and the length L ₂ are set so that the flow velocity in the pressure recovery section 42 does not fall below the flame propagation velocity. Further, the ejection speed of the primary mixed gas is controlled by the aperture d ₃ of the throttle projection 43 formed at the tip of the pressure recovery section 42 .

The flame propagation speed in combustible gas varies depending on the type of gas, the mixing ratio with air, pressure, and temperature, and is not necessarily constant. The flame propagation speed in the normal state of use is about several tens of centimeters per second, and the flow speed near the throttle protrusion 43 is set so as not to fall below this.

The primary mixed gas discharged from the tip of the primary mixing nozzle 40 becomes below the jet pressure, takes in secondary air from the secondary air flow passage 50, and is mixed in the mixed gas spouting part 63 of the secondary mixing nozzle 60. Form a gas. The diameter d ₄ and the length l ₄ of the mixed gas blowout part 63 control the amount of air taken in so that it mixes with the primary mixed gas to achieve an appropriate mixing ratio, and the flow rate of the secondary mixed gas is controlled by the flame. The speed of propagation is made sure not to fall below the speed of propagation.

The flow velocity of the secondary mixed gas discharged from the tip of the secondary mixing nozzle 60 is then reduced to a flame-enabled speed in the heat transfer tube 70 into which the tip of the secondary mixing nozzle 60 is inserted, and combustion begins. . At this time, stagnation is created on the outer peripheral side of the mixed gas jetting part 63 in the heat transfer tube 70, and a complicated vortex is created on the downstream side to maintain the flame. This results in
There is no need to form a complicated flame stabilizing mechanism in the gas ejection part 63 of the secondary mixing nozzle 60. Further, since the cooling capacity of the outer peripheral side of the mixed gas jetting portion 63 is maintained by the introduced secondary air, burnout of the burner can be prevented.

Note that the present invention is widely applicable to burners in which the combustion part gas pressure is pressurized within the pressure range by a single self-gas pressure. An injector type may be used instead of an ejector type.

(Effects of the Invention) As described above, the gas combustion burner according to the present invention converts the energy possessed by the source gas of combustion into gas velocity dynamic pressure by the fuel gas injection nozzle connected to the gas injection port of the fuel supply pipe. With this pressure, primary air for combustion is sucked in from the primary air intake port, the energy at the time of injection of this primary mixed gas is recovered by the pressure recovery part of the primary mixing nozzle, and the recovered primary mixed gas is Since the structure consists of a mechanism that converts the retained energy into gas velocity dynamic pressure by the throttle protrusion of the primary mixing nozzle and sucks in the secondary air for combustion again, the retained energy of the original gas can be significantly attenuated. Not only can the mixture ratio of fuel gas and air be adjusted to the optimum condition by forming a primary mixed gas and a secondary mixed gas sequentially, but also the energy possessed by the original gas is almost attenuated. Therefore, sufficient ejection pressure at the ignition point is maintained, the flame becomes longer and the flame can be sufficiently introduced into the heat transfer tube, etc., and other air supply means are not required and the structure can be constructed at low cost. It has excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an example of the implementation of the present invention, FIG. 2 is a longitudinal sectional view of a fuel gas supply pipe and a fuel gas jet nozzle, FIG. 3 is a right side view of FIG.
The figure is a longitudinal sectional view of the primary mixing nozzle, and FIG. 5 is a longitudinal sectional view of the secondary mixing nozzle. A... Gas combustion burner, 10... Fuel gas supply pipe, 11... Gas jetting port, 20... Fuel gas jetting nozzle, 21... Throttle part, 22... Pressure recovery part,
30... Primary air intake port, 40... Primary mixing nozzle, 41... Throttle part, 42... Pressure recovery part, 43
... Throttle protrusion, 50 ... Secondary air flow passage, 60
...Secondary mixing nozzle, 63...Mixed gas ejection part,
70...Heat transfer tube.

Claims (1)

[Scope of Claims] 1. A fuel gas supply pipe having a constriction portion having a predetermined diameter and connected to the gas nozzle of the fuel gas supply pipe, and a pressure recovery portion having a shape that widens toward the end and connected to the constriction. A fuel gas ejection nozzle, a constriction portion having a predetermined diameter that is disposed at the tip of the fuel gas ejection nozzle via a primary air intake port, a pressure recovery portion connected to the constriction portion and having a shape that widens toward the end, and the pressure recovery portion. a primary mixing nozzle having a constriction protrusion provided at the tip of the part and forming a primary mixed gas; and a secondary mixing nozzle disposed concentrically with the fuel gas injection nozzle and the primary mixing nozzle, The secondary mixing nozzle has an air intake port on the proximal end side and a mixed gas outlet of a predetermined diameter on the distal end side, and also has a secondary air flow around the outer periphery of the primary mixing nozzle to form a secondary mixed gas. A gas-fired burner characterized by forming a duct.