FR2584800A1 - Apparatus for direct reheating of all gaseous fluids (air etc.) by mixing with gases, combustion products, making it possible to obtain a perfectly homogeneous mixture - Google Patents

Abstract

The invention relates to an apparatus for direct reheating of new or recycled air, or of any other gaseous fluid, carrying out mixing of the fluid to be reheated with the combustion products of all fuels brought to the gaseous state in order finally to obtain a hot or very hot fluid at a completely homogeneous use temperature. The apparatus 1 is under pressure supplied by a centrifugal fan 4. The fluid to be reheated enters via the circuit 8, turns at 9 in order to undergo in the chamber 10 a premixing by means of a diaphragmed divergent cone 6. A front-action nozzle 7 injects a given quantity of cold fluid at great speed into the zone 11 to meet the premixture. The turbulence caused makes it possible to obtain a perfectly homogeneous mixture of fluids at 12, before leaving the apparatus. The invention finds its most important applications in the field of industrial drying, agricultural drying and surface treatments.

Description

The present invention relates to a device for direct heating of new or recycled air, or of any other gaseous fluid, by mixing the fluid to be heated and the combustion products of all fuels brought to the gaseous state. This fluid mixing device, operating under pressure, is therefore intended to produce a very homogeneous gas mixture at temperatures which can vary from 130 to 45 C. This result was made possible by the use of a diaphragm divergent cone, ensuring a premix and a front-acting nozzle terminating the mixture before it leaves the device.

The use of hot or very hot air or fluid by mixing air and combustion gases is already well known for a number of applications in industrial or agricultural drying. The great difficulty in these areas is to obtain that the mixture is as homogeneous as possible, since most of the products to be dried do not support significant temperature differences, resulting in risks of deterioration in their quality, which can be extremely expensive for users.

Indeed, the laws of physics are such that air molecules at different temperatures with different densities hardly mix and that we often use to create obstacles to turbulate the air veins by a whole panoply of baffles, turbulators, guide vanes etc ... which generate significant pressure losses for a very poor result.

When it comes to liquids at different temperatures, the problem is identical, but more easily solved by the use of agitators which stir the molecules up to the intimate mixture.

Starting from the above, the present invention aims to solve the problem of obtaining a mixture of perfectly homogeneous hot fluid from air streams or gaseous fluids having very different temperatures.

This object is achieved by means of an apparatus which, in accordance with the invention, is designed to receive on the front a gas burner with primary supply air or an oil burner and, on the other hand, the discharge of a fan which ensures the flow of air in fresh air at room temperature, or possibly in recycled fluid, necessary to obtain the desired temperature.

By this arrangement, all the circuits of the appliance are then under pressure and an air bypass is necessarily connected to the suction of the gas or oil burner, to compensate for the pressure supplied by the fan and thus allow the burner to ensure normal combustion of gas or fuel oil and to obtain good flame stability.

A first provision of this Patent is the possibility of first carrying out a premix using a divergent diaphragm cone. This diaphragm cone, divergent, has its small diameter placed at the combustion head of the burner, so that the flame develops inside. Made from refractory steel, it has a determined angle and has tangential graduated perforations so that a certain quantity of the surrounding air stream penetrates progressively and increasingly in the combustion air - gas mixture of the burner and incorporates it intimately, thus achieving the premix.

A second arrangement of this patent is the means of obtaining a perfectly homogeneous mixture of hot air, thanks to the use of a nozzle with frontal action.

This nozzle, placed on the discharge side of the fan and opposite the burner, is thus facing the flame and the pre-mixed air stream. The nozzle takes a certain amount of air at ambient temperature supplied by the fan to reject it at high speed according to a profile which diffuses it frontally.

 It follows that, thanks to the present invention, there is a frontal countercurrent encounter between the air stream or partially premixed fluid, with the combustion gases by the action of the diaphragm cone, and the quantity of air or fluid injected through the nozzle. This frontal meeting causes a very turbulent flow which, by agitating the molecules of different temperatures, makes it possible to obtain a very homogeneous mixture. In this way, the drawbacks stated above are eliminated.

The present invention may, in any case, be well understood with the aid of the additional description which follows and of the appended drawing which highlights the embodiment.

The attached drawing 1/1 is a longitudinal sectional view of an apparatus for producing direct hot air by mixing fresh air or any other gaseous fluid with the combustion gases of all fuels brought to the gaseous state by a primary supply air burner.

As shown, the sheet steel mixing device (1) comprises a sealed front plate (2) on which is fixed an oil or gas burner (3). On the opposite, is connected the discharge of a fan (4) which delivers a certain amount of air or gaseous fluid depending on the desired temperature of use. As this fan puts the appliance under pressure, an air bypass (5) is connected to the burner suction port to allow normal and stable combustion.

According to a first arrangement, a divergent diaphragm cone (6) placed at the head of the burner, includes graduated increasing and tangential perforations.

According to a second arrangement, a nozzle (7) placed on the discharge side of the fan and opposite the burner takes a certain amount of fresh air. The operation takes place as follows
The fan (4) delivers a certain amount of air or gaseous fluid which passes through the circuit (8).

At the end of this circuit, the air stream turns at (9) to enter the chamber (10). At this time, part of the air stream meets the divergent diaphragm cone (6) into which air enters through graduated tangential and increasing perforations to obtain a premix in the chamber (10). In contrast, the nozzle (7) takes air from the circuit (8) to inject it frontally at high speed at (11) to meet the premix obtained in (10). This frontal meeting against the current causes a significant turbulent flow which makes it possible to obtain in the zone (12) a flow whose temperature is then very homogeneous.

This result, obtained thanks to the invention, allows all applications of industrial drying, agricultural drying, surface treatments, etc.

without risk of significant temperature differences detrimental to the quality of the products or dried parts, which can range from their deterioration to their deterioration.

Claims (5)

1) Apparatus for direct heating of fresh or recycled air or any other gaseous fluid by mixing the fluid to be heated with the combustion products of all fuels supplied to the gaseous being, characterized in that it comprises the means d '' obtain a temperature resulting from the perfectly homogeneous mixture 2) Apparatus according to claim 1, characterized in that all of the circuits are under pressure supplied by a centrifugal fan. 3) Apparatus according to claim 1, characterized by the use of a divergent diaphragm cone (6) which allows to obtain a premix. 4) Apparatus according to claim 3, characterized in that the diaphragm cone (6) has a determined angle and comprises graduated and increasing tangential perforations. 5) Apparatus according to claim 1, characterized in that the means for obtaining a resultant temperature of the perfectly homogeneous mixture is a nozzle with frontal action (7) which injects a certain flow of air at high speed to cause a turbulent encounter of fluids hot (10) and cold (11).