EP2264365A1

EP2264365A1 - Atmospheric multigas burner

Info

Publication number: EP2264365A1
Application number: EP10164157A
Authority: EP
Inventors: Mario Provenza
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-05-27
Filing date: 2010-05-27
Publication date: 2010-12-22
Also published as: ITNA20090032A1

Abstract

The present patent application for industrial invention basically regards a multigas atmospheric burner, in particular for supplying traditional and mechanical ovens, characterized by: a) two or more torches functioning independently, characterized by a new type of atmospheric mixer; b) a system for regulation of fuel/comburent mixture, characterized by a nozzle of small size; c) a manual-opening feed valve for each torch; d) a pilot burner set in a central position, which guarantees ignition of the flame of all the torches; e) an ignition probe, which enables ignition of the flame of the pilot burner; f) an ionization probe, which, in the absence of flame, blocks fuel supply; g) a combustion head for each torch, having an inclination that varies according to the dimensions and the shapeof the oven to be supplied and a surface for outlet of the mixture that envisages a plurality of small holes all of the same size; h) two solenoid valves set in series, one of which is a slow-opening olenoid valve and one is a safety valve for providing fuel tightness; i) a protective guard with outer surface that is not smooth, which is connected to an end-of-travel system that blocks supply of fuel upon closing of the hatch; 1) a safety thermostat.

Description

The present patent application for industrial invention basically regards a multigas atmospheric burner in particular for supplying traditional and mechanical ovens, characterized by: a) two or more torches functioning independently, characterized by a new type of atmospheric mixer; b) a system for regulation of fuel/comburent mixture, characterized by a nozzle of small size; c) a manual-opening feed valve for each torch; d) a pilot burner set in a central position, which guarantees ignition of the flame of all the torches; e) an ignition probe, which enables ignition of the flame of the pilot burner; f) an ionization probe, which, in the absence of flame, blocks fuel supply; g) a combustion head for each torch, having an inclination that varies according to the dimensions and the shape of the oven to be supplied and a surface for outlet of the mixture that envisages a plurality of small holes all of the same size; h) two solenoid valves set in series, one of which is a slow-opening olenoid valve and one is a safety valve for providing fuel tightness; i) a protective guard with outer surface that is not smooth, which is connected to an end-of-travel system that blocks supply of fuel upon closing of the hatch; 1) a safety thermostat.
Innovative elements of the new burner are the new type of atmospheric mixer based upon the Venturi effect, the structure of the combustion head, the new system for regulation of the fuel/comburent mixture, and the protective guard that enables installation of the burner inside the oven.

DESCRIPTION

Forming the subject of the present invention is a burner particularly suited for supplying traditional and mechanical ovens, but not limited to this use.
The term "burner" here indicates the equipment that has the task of converting the chemical energy of a fuel into heat by activating the combustion process.
The classification of burners cannot be considered unique in so far as the criteria that can determine said classification are various; we can classify them on the basis of the thermal capacity, the structure, and the type of fuel used.
Considering a classification from the structural standpoint, it is currently possible to identify two major families of burners:

aspirated-air or atmospheric burners; and
blown-air burners.

The burner that forms the subject of the present invention falls within the family of atmospheric burners and in particular is a multigas atmospheric burner.
It constitutes an innovative professional instrument for conversion of the traditional wood-fuelled oven into a certainly more ecological version, capable of increasing productivity, reducing the running costs, reducing the consumption by regulation of the flame on the basis of the working requirements, and maintaining a higher level of hygiene in the workplace.
The purpose of the present invention is hence to overcome, thanks to a series of substantial innovative modifications, the current problems linked to the use of current burners available on the market by paying maximum attention to efficiency, adaptability, and flexibility of operation, as well as to respect for the environment both in terms of energy saving and in terms of effectiveness of the combustion process, with consequent reduction of noxious emissions.
A better understanding of the description of the present invention will be obtained with reference to the attached plates of drawings, which illustrate merely by way of non-limiting example a preferred embodiment thereof.
In the plates of drawings:

Figure 1 is a view in front elevation of the burner;
Figure 2 is a rear view once again in elevation of the same burner;
Figure 3 is a perspective view of the burner of the preceding figures;
Figures 4a, 4b and 4c, are, respectively, views in longitudinal section and in elevation of an atmospheric mixer with side fins; and
Figure 5 is a side view of the burner complete with its protective guard.

As may be seen from the attached figures (Figures 1, 2, and 3), the burner is complete with all the necessary control and safety devices and is made up of the following main elements:

two or more torches functioning independently;
a manual-opening feed valve for each torch;
a pilot burner set in a central position, which guarantees consequent ignition of the flame of the other torches;
an ignition probe, which enables ignition of the flame of the pilot burner;
an ionization probe, which, in the absence of flame, blocks fuel supply;
two solenoid valves set in series, one of which is a slow-opening olenoid valve and one is a safety valve for providing fuel tightness;
an ignition/control probe (electronic control equipment);
a protective guard with outer surface that is not smooth, which is connected to an end-of-travel system that blocks supply of fuel upon closing of the hatch so as to protect the torches from the vapour generated by baking foodstuffs in the oven.

According to a peculiar characteristic of the invention, the combustion heads of the torches and of the pilot burner can be oriented according to the dimensions and the shape of the oven to be supplied and have a surface for outlet of the mixture constituted by small holes all of the same size.
Advantageously, said characteristics concur in improving fuel/comburent mixing.
It is known that design of a combustion system is based upon two main characteristics, i.e., the flow rate of gas to the system and above all the amount of air necessary for complete combustion of the fuel.
The majority of combustion systems, prior to ignition of the process, are able to mix with the combustible gas an amount of air less than the theoretical amount required for combustion, whilst the remaining amount of air useful for achieving a complete combustion is mixed after the point of ignition. The amount of air mixed with the gas prior to the moment of ignition is called "primary air". The air mixed after the point of ignition is called "secondary air". The amount of primary air in the mixture is normally expressed in percentage of the theoretical total air required for combustion; this is commonly referred to as "aeration".
According to another characteristic of the invention, in the burner described, the system of regulation of the components of the mixture is constituted by a nozzle coaxial to the mixing tube (torch), by means of which the combustible gas is delivered, and by a manually operated valve for regulation of the air.
Said solution affords a larger useful surface for aspiration of the primary air owing to the overall dimensions of the nozzle, which are small as compared to those of burners currently available on the market.
It is moreover possible to intervene directly on the regulation of the amount of air in relation to the requirements of use of the burner, thanks to the presence of a manual-opening valve (see Figure 4).
Another characteristic of the invention regards the use of a Venturi tube in a burner for supply of traditional and mechanical ovens.
The innovation consists in the construction of a new geometry of the atmospheric mixer that is able to create a new central preferential path for passage of the fuel/comburent mixture to increase the amount of primary air aspirated and intensify the so-called Venturi effect.
The new Venturi tube, which is the main element of the burner in question, presents the innovative peculiarity of being built with two hollow fins that are opposed to one another at the restricted section, which causes increase in the speed of the mixture, recall of a greater amount of primary air within the mixer, and turbulent motion, which brings about a better mixing of the components (Figure 4).
In particular, it should be noted that, thanks to the presence of the two hollow fins, the fuel/comburent mixture assumes a helical motion throughout the body of the burner itself, so that, once the combustion head where the process takes form has been reached, it determines projection of the flame outside of the head itself, thus preventing flash-back.
Unlike the other burners currently available on the market, the head and the mixer are assembled by welding so as to reduce the thermal dispersions and improve the efficiency and performance of the combustion process.
Furthermore, present inside the combustion head is an internal screw thread capable of providing a further mixing of the components prior to ignition of the flame.
The combustion head, which is a further innovative element of the proposed burner, as has been said, is orientable according to the dimensions and the shape of the oven to be supplied. Said characteristic enables orientation of the flame so as to obtain a uniform distribution of the heat inside the oven (Figure 4).
According to a further characteristic of the invention, the plate of the combustion head, with respect to current commercially available burners that have a surface with a central hole of larger size, is characterized by a plurality of smaller holes, all of the same size.
The uniformity of said openings enables optimal distribution of the mixture over the entire surface so as to obtain improvements in combustion, facilitating the chain reaction that characterizes it.
Further advantages of the burner forming the subject of the present patent application are a better aeration of the mixture (larger amount of primary air) and total elimination of the so-called phenomenon of flash-back, which is recurrent in the majority of burners currently available on the market, thanks not only to the increase in the rate of flow of the mixture but also and above all to the presence of the longitudinal hollow fins that are warped with respect to the axial direction, i.e., arranged according to a helical path in order to impress on the gaseous mixture that traverses the burner a substantially helical (rototranslational) motion towards the outlet.
The new shape of the atmospheric mixer, the larger surface useful for aspiration of the primary air, and the uniformity of the holes on the combustion plate of the head, in combination with said hollow side fins, moreover concur in achieving perfect balance between the rate of propagation of the flame and the rate of flow of the mixture to obtain a flame that is diffused and adheres externally to the perforated plate of the combustion head.
The burner is located within the floor of the oven in a position corresponding to its mouth: precisely for this reason it is provided with a protective guard with an outer surface that is not smooth that is capable of improving adherence to the cement.
The protective guard is connected to an end-of-travel system that blocks supply of fuel upon closing of the hatch (Figure 5).
The installation of the burner in the floor of the oven guarantees both a higher standard of hygiene of the workstation, eliminating the problems of storage of wood (insects, damp, residue) and a higher level of safety, with the elimination of any object that may encumber the workstation. Said peculiarities, allied to the complete abatement of the emissions of soot into the external environment, ensure respect of all the standards of quality, safety, and environmental protection imposed by the latest community regulations.
The main technical characteristics of the burner are given in the tables below:

Thermal capacity 110 kW

Gas main supply (inches) 1"

Torch gas supply (inches) ½"

Operation Modulating, two-stage

Fuels Gaseous

Electrical supply 220V single-phase/two-phase
With reference to the attached figures, Figure 1 illustrates in front elevation the new burner forming the subject of the present patent application. In particular, in the drawing it is possible to distinguish, in each torch T, the combustion head 1, the new atmospheric mixer 2, the air-regulation system 3, the nozzle of small size 4, the gas valve 5, the safety solenoid valve 6, the junction box 8, the thermostat 9, the collector 10, the ignition probe 11, and the ionization probe 12.
Figure 2 shows the rear view of the new burner. In particular, in the drawing, it is possible to distinguish also the slow-opening solenoid valve 7.
Figure 3 is an axonometric view of the burner.
Figure 4 illustrates in longitudinal section, side view, and front view, the new atmospheric mixer 2 with the side fins 15 that are warped with respect to the axial direction. In particular, it is possible to distinguish the combustion head 1, the new atmospheric mixer 2, the air-regulation system 3, the nozzle of small size 4, and the gas valve 5.
Figure 5 is a side view of the burner equipped with the protective guard. In particular, it is possible to distinguish the protective guard 13, as well as a suitable end-of-travel system that blocks supply upon closing of the hatch of the guard 14.
To verify its effectiveness, the burner that has been described has undergone a series of tests, in different modes of use, some examples of which are provided hereinafter.

EXAMPLE 1

Following upon laboratory tests carried out on the burner, it has been found that, in steady running conditions (maximum available flow rate of fuel) and using as fuels methane or LPG, the consumption is reduced by more than 3 m³/h with respect to the average consumption of the burners currently available on the market (from 12 m³/h to less than 9 m³/h). Furthermore, there has been recorded an increase of the thermal efficiency by approximately 15%.

EXAMPLE 2

Following upon laboratory tests conducted on the burner set inside an oven for baking bread, it has been found that, in steady running conditions (maximum available flow rate of fuel) and using as fuels methane or LPG, the bread bakes faster than with burners currently in use and with a lower consumption of comburent.

EXAMPLE 3

Following upon laboratory tests carried out on the burner set inside an oven for baking pizzas, it has been found that, in steady running conditions (maximum available flow rate of fuel) and using as fuels methane or LPG, baking of pizzas and oven-baked products is faster and more uniform than with the burners currently in use.
From what has been said, it is evident that the present invention can be used in numerous fields of application, such as, for example, in automobile carburation systems, motorcycles, aeroplanes, ejectors, motors of wind-powered systems for conversion of wind power, and in the aerodynamic and aerospace fields.
Furthermore, the atmospheric mixer 2 can also be used in hydraulic industrial machines, in all types of vacuum pumps, in systems for filtration/aeration of aquariums, swimming-pools, etc.
Finally, the combustion head described so far can be used both in traditional or mechanical burners and in stoves, industrial cookers, barbecues or cooking plates, boilers for domestic and industrial energy conversion, dryers, industrial fryers, ovens for hardening and working metals.

Claims

A multigas atmospheric burner in particular for supplying traditional and mechanical ovens, characterized in that it comprises:
a) two or more torches (T) functioning independently, each comprising an atmospheric mixer (2) constituted by a Venturi tube provided, in its restricted section, with two opposed longitudinal hollow fins (15) that are warped with respect to the axial direction, and a combustion head (1) that is orientable according to the dimensions and the shape of the oven to be supplied, the surface of which for outlet of the fuel/comburent mixture envisages a plurality of small holes all of the same size; and

b) a pilot burner (P) set in a central position with respect to said torches (T), which guarantees ignition of the flame on all the torches;
thereby obtaining that the warped hollow fins (15) impress upon the gaseous fuel/comburent mixture that traverses each torch a helical movement that prevents flash-back at the combustion head (1).
The burner according to Claim 1, characterized in that it further comprises:
- a system (3) of regulation of the air of the fuel/comburent mixture comprising a nozzle (4) of small size;

- a manual-opening gas-feed valve (5) for each torch (T);

- an ignition probe (11), which enables ignition of the flame of the pilot burner;

- an ionization probe (12), which, in the absence of flame, blocks fuel supply;

- two solenoid valves set in series, one of which is a slow-opening olenoid valve (7) and one is a safety valve for providing fuel tightness (6);

- a protective guard (13) with outer surface that is not smooth, which is connected to an end-of-travel system (14) that blocks supply of fuel upon closing of the hatch (S); and

- a safety thermostat (9).
The burner according to Claim 1, characterized in that the atmospheric mixer has a length comprised in the range between 20.0 and 80.0 cm, and a width comprised in the range between 2.5 and 50.0 cm.
The burner according to Claim 1, characterized in that the hollow fins (15) are arranged at a distance comprised in the range between 15.0 and 30.0 cm with respect to the outlet of the combustion head (1), and at a distance comprised in the range between 5.0 and 15.0 cm with respect to the inlet mouth for the comburent.
The burner according to Claim 1, characterized in that the width of the hollow fins (15) is comprised in the range between 0.1-3.0 cm, and the length is comprised between 10.0 and 40.0 cm.
An atmospheric mixer (2), characterized in that it is constituted by a Venturi tube provided, in its restricted section, with two opposed longitudinal hollow fins (15) warped with respect to the axial direction, and a combustion head (1) that is orientable according to the dimensions and the shape of the oven to be supplied, the surface of which for outlet of the fuel/comburent mixture envisages a plurality of small holes all of the same size, said mixer being designed to be used in traditional and mechanical burners in stoves, industrial cookers, barbecues or cooking plates, both domestic and industrial boilers for energy conversion, dryers, industrial fryers, ovens for hardening and working metals.
The burner according to Claim 2, characterized in that the nozzle (4) with manual regulation of the fuel/comburent mixture, has a short length as compared to known ones, which is comprised between 0.5 and 5.0 cm.
The burner according to Claim 1 or Claim 2, characterized in that the combustion head (1) has a diameter comprised between 2.5 and 50.0 cm, and an inclination with respect to the horizontal comprised between 30° and 90° with respect to the axis of the atmospheric mixer (2), and preferably has a screw thread with large pitch on the inner surface.
The burner according to Claim 1, characterized in that the holes on the surface of the combustion head (1) have a diameter comprised in the range between 0.5 and 5.0 cm.
The burner according to Claim 2, characterized in that the protective guard (13) has variable dimensions, with a width comprised in the range between 20.0 and 60.0 cm, a length between 20.0 and 60.0 cm, and a height between 20.0 and 60.0 cm.