MODULATING BURNER FOR LIQUID FUELS AND MODULATING BOILER

Abstract

 The object of the present invention is a modulating burner for liquid fuels having domestic application, together with the boiler comprising said burner. The burner comprises means permitting moreover that it may be fed with gasoil C, biodiesel or vegetable oils in suitable proportions.

Description

OBJECT OF THE INVENTION

[0001] The object of the present invention is a modulating burner for liquid fuels having domestic application, together with the boiler comprising said burner.

[0002] The burner comprises means permitting moreover that it may be fed with gasoil C, biodiesel or vegetable oils in suitable proportions.

BACKGROUND TO THE INVENTION

[0003] In the state of the art, burners for liquid fuels are known which present a common configuration consisting of:

• A fuel injection pump mechanically connected to a drive motor, normally with an all/nothing working. There also exist some fuel pumps allowing a power control that permits a two speed working (all/little/nothing).
• An air combustion fan with a fixed speed mechanically connected to a common drive motor for both pump and fan.
• A fuel atomizer in a spray shape.

[0004] So, the fuel pump and the air fan are connected with a common shaft driven by the same drive motor. The airflow regulation of the fan is manually done in the boiler adjustment and it is fixed until it was manually regulated again.

[0005] The liquid fuel boilers, normally of gasoil, can also have other parts like:

• A fuel filter placed in the admission pipe.
• A fuel pre-heater, that reduces the fuel viscosity.
• A bypass in the pump to return the overfed fuel.
• A manually adjustment system for the atomizer flow and pressure.
• An (all/nothing) electro-valve to allow the fuel flow.

[0006] Modulating burners for liquid fuels are also known for the great power market, with no domestic application. They normally use compressors for the combustion air, but it makes the burner more expensive. However, these burners called modulating ones, consist of manually regulated fixed stages, not of a real continuous regulation depending on the demand.

[0007] This configuration based on prefixed stages has the problem of that the boiler, depending on the demand, has to make several stops and starts, and this thing causes a bad combustion situation with important contaminant emission rates, with an unstable comfort temperature control and with no answer capacity for a fuel composition variation demanding airflow adjustment.

[0008] They are also known the gaseous fuel boilers, they are more efficient and less contaminant, comparing with the liquid fuel boilers. The gaseous fuel burners have normally an independent drive for the fuel flow and for the airflow of the fan.

[0009] For a long time, solutions have been looking for, to solve the previous disadvantages of the liquid fuel boilers. Some of these have passed through using compressors, as described for great power applications.

[0010] The present invention solves the previous disadvantages by means of a modulating burner for liquid fuels with different drives for the fuel pump and for the fan, being both related by the air-fuel diagram and developing means allowing a fuel and air efficient mixing, also at low pressures.

DESCRIPTION OF THE INVENTION

[0011] The burner object of the invention comprises a fuel impulse means, for example a pump, a combustion air impulse means, for example a fan, and an air canalization means to improve the turbulence.

[0012] The burner object of the invention has modulating capacity, that is, it changes the flows depending on the demand. For that, comparing with the known liquid fuel boilers, the invention differs from that the fuel impulse means having a first drive motor and the combustion air means having a second drive motor, different from the first one, so there is a mechanical uncouple between the fuel pump and the fan, that is, each element has its own drive motor. The all/nothing pump is substituted by a modulating one, the fan is also modulating. The mechanical uncouple of the pump regarding to the fan permits the definition of an air-fuel diagram all along the different burner powers. This configuration permits the airflow adjustment in real time by changing the fan speed to adapt the inlet fuel needs in the application.

[0013] There is a relationship between the first and the second drive motor so that an air-fuel diagram permits the mixing airflow adjustment to adapt the inlet fuel needs in the application.

[0014] However, there is the technical problem of adapting an effective solution as for the gaseous fuels, for the liquid fuels application, because when the modulating fuel pump is working at low pressures is difficult to keep the fuel spraying quality, becoming an ineffective combustion.

[0015] This technical problem is solved in the invention, by including in the burner in addition a canalization means for the air generated by the fan to improve the turbulence in the outlet zone of the air impulse means, with the addition of the fuel in that zone. The canalization means combine air and fuel and keep the spraying quality so that permits improving the burner modulating capacity, keeping the flame stability and the low contaminant emission rates.

[0016] The burner object of the invention can be used by a mono-fuel boiler, with gasoil C for example, and by a multi-fuel boiler, using other elements in addition like a viscosity sensor and an oxygen sensor, giving means to the boiler to be ready for the kind of inlet fuel.

[0017] The boiler comprising a burner with the above technical characteristics is also object of the present invention.

DESCRIPTION OF THE DRAWINGS

[0018] This descriptive report is complemented by some drawings, showing the preferred example and never restrictive of the invention.

Figure 1 is a diagram of an embodiment example of the burner object of the invention, for a mono-fuel boiler.

Figure 2 is a diagram of an embodiment example of the burner object of the invention, for a multi-fuel boiler.

Figure 3 is a diagram of an embodiment example of the air canalization means to improve the turbulence.

PREFERRED EMBODIMENT OF THE INVENTION

[0019] Figure 1 shows an embodiment example of a burner for a mono-fuel boiler, the fuel is gasoil C normally.

[0020] There is a fuel tank (7), followed by a filter (8) that feeds a pump (1) driven by a first drive motor (4). The pump (1) feeds a pre-heater (9), and this (9) feeds an atomizer (3). The burner also has a fan (2) driven by a second drive motor (5), and the fan (2) feeds the burner tube (10). An electronic card (6) having the air-fuel ratio, permits the adjustment of the drive motors (4,5) depending on the demand.

[0021] Figure 3 shows an embodiment example of the improving turbulence means in the fan (2) outlet. These means are a connecting part (11) of the fan (2) with the burner tube (10). The connecting part (11) causes a spiral airflow from the fan (2), helping the atomizer (3) stability in a wider power level.

[0022] The modulation of the power permits to find the necessary air and fuel flow depending on the thermical demand, according to this the fan (2) speed is modulated with the speed reading of its own, and is set a fuel flow instruction through the power-air-fuel diagram for the modulating pump (1) working.

[0023] The burner object of the invention permits also its use with several kind of fuels. This could permit the boiler being fed with bio-fuels with no burner adaptation needed, even it could be fed with vegetable oils because the combustion system permits an automatic adjustment to the unsettled bio-fuel characteristics. The boiler comprising a burner object of the invention could be fed with gasoil C in 100% proportion, with biodiesel in any proportion, even raw oils could be added if necessary.

[0024] In case of the boiler could be fed with different fuels, here the burner could be as shown in figure 2 for a multi-fuel boiler, the ratio between the viscosity and the flow of the fuel is looked for. Because is not possible to find automatically the fuel origin, the necessary flow variation for an efficient combustion is found in this way. For the viscosity measurement, the burner has a viscosity sensor (12).

[0025] The viscosity sensor (12) measures the fuel viscosity and the fuel temperature, and with these data finds the necessary flow. This permits the boiler to work with different kind of fuels, independently of its viscosity, because it detects the kind of fuel and adapts itself to them.

[0026] In addition, the burner comprises an oxygen sensor (13), this sensor measures the oxygen in the combustion fumes, and consequently has the function of controlling and readjusting the air excess depending on the percentage of oxygen in the fumes. So, the objective is a minimum pollution and a maximum performance/efficiency.

[0027] The basic diagram of the gasoil is used in the preferred embodiment, in order to find the flow, because the other bio-fuels are more viscous generally.

[0028] The boiler comprising the burner object of the invention is suitable for hot water and heating, and it is modulating, that is, it adapts to the demand and it can be multi-fuel, that is, gasoil C, biodiesel and mixing of gasoil C with vegetable oil.

Claims

1. Modulating burner, comprising

• fuel impulse means,

• combustion air impulse means,

• air canalization means to improve the turbulence,

characterised in that
the fuel impulsion means have a first drive motor and the combustion air impulse means have a second drive motor, different from the first one, both drive motors are related to each other so an air-fuel diagram permits the airflow adjustment of the mixing be adapted to the inlet fuel needs in the application, comprising also a fan generated air canalization means to improve the turbulence in the outlet zone of the air impulse means, with the addition of the fuel in that zone.

2. Modulating burner, according to claim 1, characterised in that the fuel impulse means consist of a pump (1).

3. Modulating burner, according to any of the previous claims, characterised in that the combustion air impulse means consist of a fan (2).

4. Modulating burner, according to any of the previous claims, characterised in that the air-fuel mixing injection means consist of an atomizer (3).

5. Modulating burner, according to any of the previous claims, characterised in that the air canalization means cause a spiral airflow inside itself.

6. Modulating burner, according to claim 5, characterised in that the air canalization means comprise a connecting part (11) placed between the air impulse means and the combustion chamber.

7. Modulating burner, according to claim 2, characterised in that comprises means for the fuel viscosity measuring and for the fuel temperature measuring to set the flow of fuel before be introduced in the injection means.

8. Modulating burner, according to any of the previous claims, characterised in that comprises an oxygen sensor (13) for the outlet combustion fumes to find the necessary adjustments of the combustion airflow.

9. Modulating boiler for liquid fuels, characterised in that comprises a burner, according to any of the previous claims.

Drawing