LAMINATED BURNER STRUCTURE

Abstract: The invention relates to a burner (1) for a heating device, said burner being provided with ducts (6) for the supply of a mixture of gaseous fuel and air. The burner is made up of a number of plate-type elements (2, 3) which are placed against each other and are connected to each other to form a unit. The elements define ducts (4) through which a cooling medium can flow. The mixture of gaseous fuel and air is preferably fed to the combustion surface through straight ducts (6), said ducts having a length which is longer than any lateral dimension thereof. Preferably the ducts (4) for the cooling medium are situated at least partially near the combustion surface of the burner (1).

Description: The invention relates to a burner for a heating device, said burner being provided with ducts for the supply of a mixture of gaseous fuel and air. Such a burner is generally known in a large number of embodiments, and is used, for example, in a central heating system for heating central heating water, in a geyser for heating domestic water or in a combined heating device for heating central heating water as well as domestic water (see for example, US-A-2 484 123). A disadvantage of the known burners, which are usually produced from formed plate material, is their generally high flame temperature which leads to high No x concentration in the flue gases of the burners. This is undesirable from a point of view of fighting environmental pollution. Beside the burners mentioned before, low-NO x burners are known, but a disadvantage of these burners is the turbulency of the flame, which makes the flame difficult to stabilize. The reason for this is that the stabilization is attained by heating the combustion surface which at a change of delivered power takes a certain amount of time and leads to a change in combustion surface temperature. The last-mentioned effect shortens the life time of the burner. An object of the invention is to provide an improved low-NO x burner. This object is achieved according to the invention in that the burner is made up of a number of plate-type elements which are placed against each other and are connected to each other to form a unit, said elements defining ducts through which a cooling medium can flow. Constructing a burner from plate-type elements makes it possible to very simply form ducts separated from each other in the burner for the supply of the mixture of gaseous fuel and air on the one hand and a cooling medium on the other. Of course, different ducts may contain different cooling media, if convenient. The use of a cooling medium is particularly advantageous, because firstly the gas/air mixture can be cooled with the cooling medium before combusting it, and secondly the combustion surface can be cooled with the cooling medium. Both measures result in a reduced flame temperature, which in turn results in a relatively low production of NOx at the combustion. In a preferred embodiment of the burner according to the invention the gas/air mixture flows to the combustion surface through long, straight ducts. Accordingly, a laminar flow of the gas mixture can be attained, which yields a laminar flame as well that can be stabilized and modulated particularly well over a large power range. Instantly after ignition the flame is stable, and instantly the NO x - concentration in the flue gases is low. Moreover, the flame stays stable under all working conditions. It has been found that the ratio between the smallest and the largest power to be set may be 1 : 10, under which largely varying working conditions, the temperature of the combustion surface may, due to the operation of the cooling medium, remain stable at, for example, 60°C. This has a very favourable effect on the life time of the burner. To obtain a well-cooled combustion surface, the ducts for the cooling medium are situated advantageously at least partially near the combustion surface of the burner. The invention is illustrated in more detail with the aid of the drawing, which in a single figure shows a preferred embodiment of the burner according to the invention in a schematic perspective view. In the figure the burner 1 is made up of a number of plate-type elements 2 and 3 which are placed against each other and are connected to each other to form a unit. Each of the elements 2 or 3 in itself can be made up of thinner plate-type elements to obtain the desired structure and dimensions. The elements 2 contain a duct 4, the course of which is indicated with a dashed line. A cooling medium can flow through the duct 4 in the direction of the arrows at the duct inlet and outlet side. The elements 3 are provided alternating with the elements 2, and comprise a number of strips 5 which are placed in a vertical direction and define ducts 6 for the supply of a mixture of gaseous fuel and air, the mixture being fed in the direction of the arrows near the duct inlet side and being combusted with laminar flames 7 at the opposing side of the burner 1. The cooling medium flowing through the ducts 4 cools the burner and particularly the supply ducts for the gas/air mixture and the combustion surface at the foot of the flames 7.

Claims: Burner (1) for a heating device, made up of a number of alternating first and second plate-type elements (2, 3) which are placed against each other and are interconnected to form a unit, said second plate-type elements (3) defining ducts (6) through which mixture of gaseous fuel and air can flow to a combustion surface of the unit, said first plate-type elements defining ducts (4) through which a cooling medium can flow, characterized in that the ducts (6) through which a mixture of gaseous fuel and air can flow as well as the ducts (4) through which a cooling medium can flow are each situated in their entirety in one plate-type element (3, 2), the axes of the ducts (6, 4) extending in the plane of the plate-type elements (3, 2). Burner according to claim 1, characterized in that the ducts (6) for a mixture of gaseous fuel and air are straight and extend from a duct inlet side at one edge of a plate-type element (3) to a duct outlet side at the combustion surface at the opposing edge of the same plate-type element (3). Burner according to claim 1 or 2, characterized in that means are provided to apply a different cooling medium to different plate-type elements (2) on either side of a plate-type element (3) with ducts (6) through which a mixture of gaseous fuel and air can flow.

Inventors: VLOON, PAULUS JACOBUS, WIERENGA, HENDRIK JACOB LAMMERT
Applicants: NEFIT FASTO B.V.
Application year: 1990
Main classification: F23D14
IPC codes: F28D9, F23C99, F23D14, F24H1, F24H8