EP0822375B1 - Nozzle for blowing secondary air in a combustion furnace - Google Patents

Description

The present invention relates to a nozzle blowing secondary air into a combustion furnace.

It relates more precisely to a nozzle of blowing secondary air into a combustion furnace comprising a box of rectangular section made up of four facing walls two by two said first walls and second walls and pivoted by means of a member of control along an axis known as a traversing axis of rotation said first walls, the box being open on two opposite faces, one being the air inlet face and the other the outlet face of this air in the hearth.

Vertical series of such superimposed nozzles are generally installed at the four corners of the combustion at the top of the burner boxes and are used to balance the temperature inside the fireplace and thus can allow the reduction of oxide emissions nitrogen.

It is known to install orientable nozzles vertically so that secondary air can be blown out on a vertical range. To do this, they consist a rotary box on a horizontal axis thanks to a arrangement of studs arranged on the first walls vertical of this box, the rotation being actuated by a control member consisting of a rod fixed so articulated on one of these walls above the axis of rotation and pull or push to orient the nozzle.

Such a nozzle is described in the document of Patent FR-2,689,211 filed by the Applicant on March 30, 1992.

Now it turns out that there exists with such a system of blowing non-uniform temperatures in the fireplace, nozzles blowing air only over a space of constant horizontal dimension and no air can be blown laterally to this space.

The invention allows the temperature to be adjusted in the entire focus, allowing adjustment of the orientation horizontal outgoing air flow, without modification of the existing vertical orientation arrangement.

To do this, according to the invention, a flap structure perpendicular to the second walls is arranged in the box, each of the flaps being pivotable thanks to an actuation arrangement according respectively to a axis perpendicular to the axis of rotation and intersecting it.

Thus is obtained an optimal functioning of the hearth of combustion for example of a heating boiler tangential of great power, allowing to have a balanced steam temperature at the outlet of the boiler. In addition, thanks to the adjustment of the air supply angle secondary it is possible to decrease emissions nitrogen oxides more efficiently.

According to the preferred embodiment, said flaps are parallel and integral.

Advantageously, said actuation arrangement is connected to a shutter and consists of a clevis hinged on the shutter along an axis perpendicular to this shutter and mounted rotatable around its longitudinal axis on a workpiece articulated on a sliding actuation shaft according to its longitudinal axis and parallel to the second walls.

Preferably, the box is made of sheet metal wavy.

The box can be reinforced on the outlet face of bars integral with the second walls and parallel to the first walls.

The invention is described below in more detail at using figures representing only one embodiment preferred of the invention.

Figure 1 is a horizontal sectional view of a combustion hearth.

Figures 2A and 2B are vertical section views a blowing nozzle according to the invention, in upright position and in an upward facing position.

Figures 3A and 3B are sectional views horizontal of a blowing nozzle conforming to the invention, in a straight position and in a position oriented towards the right.

Figure 4 is a cross-sectional view of detail.

Figure 5 is a front view of a nozzle blowing according to the invention, seen from the side of the combustion.

The combustion hearth 1, represented in FIG. 1, of rectangular horizontal section has four corners of the burner boxes 2 fitted with secondary air supply 3. These burner boxes are consisting of series of nozzles superimposed on one part the height of the fireplace.

If they are only orientable vertically as in the prior art, these nozzles 3 blow air secondary on spaces 4 of horizontal dimension constant. There are then spaces 5 in the hearth in which cannot be injected with secondary air and where the temperature cannot be regulated.

Thanks to the invention, these nozzles 3 are also horizontally orientable without modification of the vertical adjustment arrangement and therefore are orientable in all directions and it is possible to adjust the temperature in the entire fireplace.

To do this, the nozzles 3 are preferably designed as shown in the other figures.

The blowing nozzle 3 comprises a box 6 of rectangular section consisting of four facing walls screws two by two, two vertical walls 6A called first walls and two walls slightly inclined with respect to the horizontal 6B said second walls, advantageously in corrugated sheet in order to be slightly deformable under the effect of temperature. Box 6 is open on two sides opposite, one being the 6D inlet face of the air and the other the outlet face 6C of this air in the hearth.

The box 6 is supported by a support structure 8 and can be rotated by means of a control member according to a horizontal axis 7 said axis of rotation passing through said first walls 6A. This control member is made up a rod 9 hingedly attached to one of the walls vertical 6A above the axis of rotation 7 and drawn or push to vertically orient the box 6 which can pivot thanks to an arrangement of tenons arranged on the vertical walls 6A of this box 6.

The box 6 is reinforced on the outlet face 6C of bars 11 integral with the inclined walls 6B and parallel with vertical walls 6A.

A structure 12 of flaps perpendicular to the walls 6B is inclined in box 6. This structure 12 consists of flaps 12A, 12B parallel and secured by means of flat profiles 12C, 12D on which the shutters are connected.

Each of the flaps 12A, 12B is pivotable on two pivoting joints 20A and 20B arranged on the second walls 6B of box 6 thanks to an arrangement actuation along an axis 13 respectively perpendicular to the axis of rotation 7 and cutting it.

This actuation arrangement is connected to a flap, advantageously the central flap 12A and consists of a yoke 14 articulated on the flap 12A along an axis perpendicular to this flap 12A and rotatably mounted around its longitudinal axis on a part 14A articulated on a horizontal actuating shaft 15 sliding along its axis longitudinal and supported by guide rings 18 held by gussets 19 on the support structure 8. More specifically, the part 14A is a flat profile provided of an oblong light 16 receiving a tenon 17 passing through the shaft 15 as shown in FIG. 4.

It is thus possible to adjust the orientation vertical of the secondary air flow by maneuvering the rod 9 by pushing or pulling it and adjusting its horizontal orientation by sliding the shaft 15. These two adjustments can be made simultaneously which allows orientation in all directions. In addition, the horizontal orientation arrangement can be installed on an existing orientation nozzle vertical.

Claims (5)

1. A nozzle for blowing secondary air into a combustion hearth, the nozzle comprising a rectangular section box (6) constituted by four walls facing each other in pairs, referred to as "first" walls (6A) and as "second" walls (6B) and capable of being turned about an axis of rotation (7) by means of a control member, the axis of rotation passing through said first walls (6A), the box being open via two opposite faces (6C, 6D), one being the inlet face (6C) for air and the other being the outlet face (6D) for air going into the hearth, the nozzle being characterized in that a structure (12) of flaps is disposed in the box (6) perpendicularly to the second walls (6B), each of the flaps (12A, 12B) being capable of being turned by an actuator arrangement about a respective axis (13) perpendicular to the axis of rotation (7), and intersecting the axis of rotation (7).
2. A nozzle according to claim 1, characterized in that said flaps (12A, 12B) are parallel and secured to one another.
3. A nozzle according to claim 2, characterized in that said actuator arrangement is connected to one of the flaps (12A) and is constituted by a fork (13) hinged to said flap (12A) about an axis perpendicular to said flap and is mounted to rotate about its longitudinal axis relative to a piece (14) hinged on an actuator shaft (15) that is slidable along its longitudinal axis which is parallel to the second walls (6B).
4. A nozzle according to any preceding claim, characterized in that the box (6) is made of corrugated sheet metal.
5. A nozzle according to any preceding claim, characterized in that the box (6) is reinforced at the outlet face (6C) by bars (11) secured to the second walls (6B) and parallel to the first walls (6A).

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