JPS6033405A - Combustion furnace - Google Patents

Abstract

PURPOSE:To prevent the flow of burner flames from deviating by the negative pressure produced between the injected flames and the wall of a furnace, by providing injection ports to recirculate gas on the walls of a furnace on the side where burner flames will come near while they are swirling. CONSTITUTION:Burner 2 provided in four corners of a furnace 1 are designed to introduce injected combustion air and recirculating gas so as to be able to flow coming in contact with a virtual circle 11 in the center of a furnace 1. But the burner flames near the burner 2 are apt to come close to the walls of a furnace while they are swirling. To prevent the flames coming near the walls, recirculating gas injection ports 10 are provided to each wall on the side where flames come near to it. The recirculating gas is injected from each port 10. A satisfactory effect has been proved by injecting surplus recirculating gas in the degrees of 3-10% out of the quantity of gas generated by combustion into the furnace from said gas injection ports.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tangential firing type combustion furnace.

In the recent tangential firing type combustion furnaces where NOx countermeasures have been strengthened, unlike the conventional gas recirculation method where gas is introduced into the bottom of the furnace,
In order to significantly reduce Ox, the entire amount of these gases is recirculated through the burner port.If we outline the combustion furnace using Figures 1 and 2, there are burners at the four corners of the combustion chamber 1. 2 and a burner wind box 2' are arranged, and a heat exchanger 3 such as a superheater is installed at the furnace outlet, and finally a economizer 4 is installed, and the exhaust gas passes through the economizer and then The air passes through a preheater 8, in which a forced fan 9
A part of the gas is introduced into the furnace again by the gas recirculation fan 5. This recirculating gas is divided into a recirculating gas mixed system 6 for NOx reduction and a separate recirculating gas system 7, but both systems enter the burner wind box and are injected into the furnace from the nozzle part of the burner. It looks like this. In this way, by blowing out a large amount of combustion air and recirculated gas from the burners 2 at the four corners of the furnace, a layer of gas corresponding to the height and width of the burner flows toward the center of the furnace. The mounting angle of the burner 2 is determined so that the direction of air and gas ejection is tangent to the imaginary circle 11 at the center of the furnace (Fig. 2), but in reality, the air flow is drawn to the furnace wall and follows the intended tangent line. The combustion gas flow in the furnace also tends to be biased toward the peripheral wall, and due to the unbalance of the gas flow in the furnace, the heat absorption performance of the heat exchanger 3 placed on the downstream side is affected. However, there are various drawbacks such as the occurrence of unbalance phenomena.

This invention was made in view of the current situation, and it solves the drawbacks of the conventional method by disposing a recirculation gas inlet in the furnace wall on the side that approaches the burner when the burner flame rotates. The purpose is to provide a combustion furnace that has been removed.

Next, to explain the drawings showing the embodiments of the present invention, in FIGS. 3 and 4, combustion air and recirculated gas are arranged at the four corners of the combustion chamber 1 and are arranged in a virtual circle around the center of the furnace.
A recirculating gas inlet 10 is disposed on the furnace wall on the side where the burner flame near the burner 2 whose ejection direction is oriented so as to touch the furnace wall rotates, and the recirculating gas is injected from the gas inlet. In Fig. 4, 12 is the front wall of the furnace, 13 is the right side wall of the furnace, 14 is the rear wall of the furnace,
and 15 are the same left side walls.

Therefore, according to the present invention, the direction in which the combustion air and recirculation gas are ejected from the burner 2 is set at the virtual circle 1 at the center of the furnace.
1, but the reason why the flow actually approaches each furnace wall side in the swirling direction is because negative pressure is generated between the ejection direction and the furnace wall, and within the negative pressure region. When recirculating gas is introduced from the recirculating gas inlet 10 in the recirculating gas inlet 10, the pressure within the area becomes positive, so that the burner 2 is moved in the tangential direction of the virtual circle as originally planned without causing the drifting phenomenon. Combustion air etc. are blown out from the combustion chamber, thereby eliminating the drawbacks of the prior art. It has been found through experiments that a sufficient effect can be obtained by injecting surplus recirculated gas in an amount of about 3 to 10 g of the amount of combustion gas generated through the gas inlet.

Next, in FIGS. 5 and 6 showing other embodiments of the present invention, a recirculation gas inlet 10 of only one step height is provided near the lowest stage burner 2, and the amount of gas input is as follows. An amount of 2 to 5q6 of the amount of combustion gas is sufficiently effective.

Incidentally, the same effect can be obtained even if it is installed only at three opposite corners of the four corners of the furnace wall.

Furthermore, as shown in FIGS. 7 and 8, in still another embodiment of the present invention, a recirculation gas inlet 10 may be arranged at the bottom of the furnace, and the amount of gas injected is 3 to 3 of the amount of combustion gas. b. It can be effective.

In the above embodiment, a part of the combustion gas is used as the fluid sent from the inlet, but the same effect can be obtained even if part of the combustion air is used instead of the gas. Needless to say, you can get it.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing a longitudinal side view of a tangential firing type combustion furnace, Figure 2 is an explanatory diagram showing a plane view across the combustion chamber from the previous time, and Figure 3 is an explanatory diagram showing a side view of a tangential firing combustion furnace. FIG. 4 is an exploded view of the furnace wall, and FIG. 5 is an explanatory view of the furnace wall showing another embodiment of the invention. Developed diagram,
FIG. 6 is an explanatory diagram showing the main parts of the combustion furnace, FIG. 7 is an explanatory diagram showing the arrangement of the recirculation gas inlet showing still another embodiment of the present invention, and FIG. It is also a developed view of the furnace wall. 1... Combustion chamber, 2... Burner, 2'... Burner style box, 3
...Heat exchanger, 4.Economy device, 5.Recirculation fan, 6
... Recirculation gas mixing system, 7. Separate recirculation gas system, 8. Air preheater, 9. Forced fan, 10.
Recirculation gas inlet, 11...Furnace center imaginary circle, 12...
Furnace front wall, 13... Same right side wall, 14... Same rear wall, 15...
- Same left wall.

Claims (1)

[Claims] In a tangential firing type combustion furnace,
A combustion furnace characterized in that a recirculation gas inlet is provided in the furnace wall near the burner and on the side where the burner flame approaches by swirling.