The use of ejector equipment for mixing fuel and combustion air is prior known.

An object of the present invention is to provide an improved ejector nozzle, capable of enhancing the entrainment of secondary combustion air with respect to prior art solutions. In order to achieve this object, an ejector nozzle of the invention is characterized in that the nozzle is provided with an annular outer space for a combustible mixture of fuel and primary combustion air, and with means for feeding the fuel and/or primary combustion air in a direction transverse to the longitudinal axis of the nozzle into said annular space for setting the mixture present in the annular space in a rotating motion.

The ejector nozzle of the invention, wherein a mixture of fuel and primary combustion air is set in a rotating motion in an annular space by feeding fuel and/or primary combustion air into the annular space in a direction transverse to the longitudinal axis of the nozzle, is capable of achieving a rotating motion more effective than what is achieved by a so-called Vortex-ejector, in which a rotating motion is created by means of blade elements and which is not provided with said annular space.

Claim 2 discloses a tubular central space, which is connected to a source of secondary combustion air and which can be used for increasing the total amount of secondary combustion air substantially as compared to the entrainment of secondary combustion air effected only from outside the nozzle.

The invention will now be described in more detail with reference made to the accompanying drawings, in which:

fig. 1 shows one embodiment for an ejector nozzle of the invention in a longitudinal section, and fig. 2 shows the embodiment of fig. 1 in a frontal view.

Referring to figs. 1 and 2, an ejector nozzle 1 of the invention inclues an outer annular space 3, which is supplie with fuel and/or primary combustion air from a duct 2 in a direction transverse to the longitudinal axis of the nozzle for setting the mixture in a rotating motion in the annular space. The mixture of fuel and primary combustion air burns in the annular space 3 and discharges at a high velocity out of the forward end (arrows 5) of the nozzle through an orifice 8. The annular space 3 has a cross-section which is adapted to converge towards the orifice 8 for a higher discharge speed. Inside the annular space 3 is designed a tubular central space 4, which is connected to a source of secondary combustion air, e. g. to an atmosphere surrounding the ejector. In a normal case, the nozzle 1 is used in such a way that secondary combustion air is entrained both from around the nozzle 1 (arrows 7) and from the central space 4 (an arrow 6).

However, it is possible to operate the nozzle the way of a normal ejector nozzle, such that the secondary combustion air is only entrained from around the nozzle, the central space being sealed, or, optionally, it is conceivable to entrain secondary combustion air only through the central space 4.

It has been established by mathematical calculations that the inflow ratio between a secondary flow and a primary flow is about 7 when the secondary flow is only entrained from outside a nozzle. When a central space is also used for feeding the secondary flow, said inflow ratio is about 10-11. In mathematical calculations, the primary feed has been given the following values: mass flow rate 0,374 kg/s temperature 550°C density 0,420 kg/m3 linear speed 210 m/s mass flow rate per unit area 87,41 kg/m2s

fuel concentration 5,37 % by weight and the secondary feed has been given the following values: pressure 1 bar temperature 25 ° C density 1.13 kg/m3 fuel content. 0.00 % by weight The ejector nozzle of the invention can be used for a variety of applications, such as for producing hot drying air, feeding hor combustion air to a combustion unit, etc.

The above description deals with one ejector nozzle of the invention by way of an example, and that is not intended to limit the scope of protection as defined in the following claims. It is also conceivable to design the nozzle structure e. g. in such a way that the tubular central space is replace by a solid component, the nozzle operating the same way as a normal ejector nozzle, but at a higher intensity by virtue of a transverse feed into the annular space and a rotating motion in the annular space achieved thereby.