JPS5817364B2 - Low NOx radiant tube burner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low NOx radiant tube burner.

In radiant tube burners, as with other burners, various methods are employed to suppress the amount of NOx generated from the viewpoint of pollution prevention.

One effective method is the exhaust gas circulation method.

However, this method requires special equipment and the like as means for recirculating the exhaust gas, and also requires recirculating gas piping.

Therefore, converting an existing radiant tube burner to one of the exhaust gas circulation type has the disadvantage that the cost increases accordingly.

Further, since the recirculated exhaust gas is cooled down to a low temperature in the piping, a problem arises in that efficiency is reduced in terms of thermal efficiency.

The present invention has been made in order to eliminate the above-mentioned drawbacks of the conventional technology, and it achieves the same effect as exhaust gas circulation without obscuring the exhaust gas, does not require a special exhaust gas circulation device, and replaces only the existing burner. The present invention aims to provide a burner that can be made into a low NOx radiant tube with no loss in thermal efficiency.

Next, the present invention will be explained according to the drawings which are examples.

In FIG. 1, 1 is a furnace wall, and 2 is a radiant tube.

3 is a burner body, and a casing 4 attached to the tube 2 has a combustion air supply port 5 and a fuel nozzle 6.

As previously mentioned, the material nozzle 6 has a slightly larger diameter at the front of the main ejection lower tip, and there are many primary ejection ports 8 in this part.
is the provision.

Reference numeral 9 denotes a cylindrical body serving as a partitioning means provided between the fuel nozzle 6 and the casing 4, the tip of which is used to effectively direct the combustion gas of the fuel from the primary jet nozzle 8 to the jet of fuel from the main jet lower. It is provided so as to protrude to the surrounding position and forms passages 11 and 12 on the outside and inside thereof.

The two reverse passages 11 and 12 communicate with each other through an opening 10 provided in front of the primary ejection port 8.

Further, the total opening area of the openings 10 is such that the fuel from the primary injection port 8 is produced in the cylinder body 9 to produce combustion gas with a low 02 temperature.

Note that 13 is a pilot burner. Next, combustion in the burner having the above configuration will be described.

When air is supplied from the combustion air supply port 5 and fuel is supplied from the fuel nozzle 6 and ignited by the pilot burner 13, the fuel (approximately 10 to 40% of the total fuel) jetted from the primary jet port 8 flows into the opening 10. It burns in the air that flows, generating low 02 combustion product gas, and this gas flows into the flame 1 from the main blowout lower.
Surround 4.

Therefore, this flame 14 performs reductive combustion using the combustion product gas and sequentially mixes it with the secondary air from the passage 11, that is, performs low NOx combustion.

Note that the cylinder 9 is connected to the fuel nozzle 6 as shown in FIG.
An annular diffuser 9a may be provided in front of the primary ejection port 8 to create a combustion air flow so that the combustion generated gas from the primary ejection port 8 is in the state as described in the previous embodiment.

15 is a hole.

Furthermore, it is better to burn the primary fuel quickly and efficiently through the primary jet nozzle 8 by using a method that allows for good mixing with air (i.e., a premixing means in front of the combustion nozzle, etc.). Preferably, by making it in this way, 1
The secondary ejection port 8 can be advanced close to the main ejection lower and made almost integral with the main ejection lower.

However, in this case, it is preferable to keep the combustion of the primary injection port 8 away from the main injection lower in the circumferential direction so as not to integrate it with the combustion of fuel by the main injection lower.

As explained above, the combustion effect of the fuel in the two stages of the primary jet nozzle 8 and the main jet lower of the present invention is similar to that of the first embodiment, and the effect of combustion of the fuel in the two stages of the primary jet nozzle 8 and the main jet lower is similar to that of the first embodiment.

Even if the diffuser 9a in the embodiment is not used, the effect can be produced by providing it further on the combustion air supply side than the main jet lower, but the effect is clearly exhibited by adding the means as in the embodiment. It was designed so that

As is clear from the above explanation, in the present invention, a primary jet nozzle is provided before the main jet nozzle of the fuel nozzle, and this part generates combustion gas consisting of the same components as the exhaust gas. Since the radiant tube is surrounded and combusted, it is possible to achieve low NNOx while performing combustion with a soft, elongated flame characteristic that is highly uniform in heating the radiant tube through slow combustion similar to conventional exhaust gas circulation.

Furthermore, since the combustion gas from the primary combustion is directly generated within the burner body, its temperature does not decrease, and the main flame can be heated to a high temperature, thereby increasing thermal efficiency.

Furthermore, as explained above, the fuel is divided into primary and earth excavation,
The stepwise combustion method improves complete combustion in low excess air combustion, and this point is particularly noticeable in low furnace temperature and low capacity combustion.

Further, since no special equipment or piping is required, the present invention has the remarkable effect that it is possible to create a low NOx radiant tube by simply replacing the burner with the existing radiant tube as it is.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are both sectional views of the burner of the present invention. 1...Furnace wall, 2...Radiant tube, 3...
Burner body, 4...Casing, 5...Combustion air supply port, 6.6a...Fuel nozzle, 7...Main jet port, 8...Primary jet port, 9...Cylinder Body, 9a... Diffuser, 10... Opening, 11, 12... Passage.

Claims (1)

[Claims] 1. A two-stage fuel injection nozzle having a main injection port at the tip and a primary injection port on the front side of the injection port is installed approximately at the center of the air supply pipe, and a part of the fuel is supplied from the primary fuel injection port. 1. A low NOx radiant tube burner, characterized in that the low NOx radiant tube burner is configured such that the low 02 concentration gas generated by the combustion surrounds the main jet of fuel from the main fuel injection port.