ES2539246B1 - SOLID FUEL VERTICAL BOILER - Google Patents

Abstract

The present invention consists of a vertical boiler that works with solid fuels, such as biomass, coal, wood, etc. The boiler comprises a home divided into two sections. A lower section, where a partial combustion of the solid fuel is achieved, and an upper section, where, thanks to the introduction of a secondary air flow, the combustion of the gases generated in the lower section is completed. Between both sections of the home there is a narrowing that allows to increase the speed of the gases of the partial combustion for its mixing with the secondary air flow to complete the combustion.

Description

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DESCRIPTION

Vertical solid fuel boiler. OBJECT OF THE INVENTION

The present invention is encompassed in the field of vertical boilers, that is, with the home arranged in a vertical position, operating on solid fuels, such as biomass, coal, wood, etc.

Said invention fundamentally proposes a boiler comprising a home divided into two sections. A lower section, where a partial combustion of the solid fuel is achieved, and an upper section, where the combustion of the gases generated in the lower section is completed.

Between both sections of the home a narrowing is arranged that allows to increase the gas velocity of the partial combustion before mixing with the secondary air flow to complete the combustion.

BACKGROUND OF THE INVENTION

In reference to the state of the art, it should be mentioned that different types of boilers are known and marketed for both domestic and industrial use.

Boilers for burning solid fuel generally comprise a dispenser that delivers solid fuel to a home or combustion chamber.

At the bottom of the home there is a grill on which solid fuel is burned. Said grill is also capable of retaining and unloading the ashes towards an ashtray located below it.

The combustion exhaust gas generated in the home passes through a heat exchanger transferring said heat to the water for later use, for example, in heating systems, domestic hot water, etc.

In order to carry out the combustion of the solid fuel deposited on the grill it is necessary to supply said combustion chamber with a certain amount of air.

The combustion technology currently used in solid fuel boilers includes a gasification phase (incomplete combustion) of the fuel arranged on the grill, using a primary air flow that penetrates the bottom of the home, in the opposite direction to the introduction of the solid fuel, passing through the bed of said solid fuel deposited on the grill.

Subsequently, a complete or total combustion phase is carried out, where a second quantity of the air necessary to complete the combustion of the gas generated in the previous phase is provided.

For example, in patent document EP 2083215, published on July 29, 2009, shows a vertical domestic boiler fueled by granular biomass fuel, such as pellets.

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The boiler comprises a home made up of one or more vertical parts, which are formed with cross sections with a certain and different geometry to achieve the rise of combustion gases at a certain speed that guarantees that these gases remain inside the home until its complete combustion has been achieved.

The home is arranged inside a chamber through which the air for combustion circulates, which arrives at the home through the grill, and especially, through conical holes made in the wall of the home.

The present solution has the disadvantage that the secondary air flow is not injected in such a way that it creates a turbulence that facilitates it to mix completely with the gases, with a view to achieving the complete combustion of said gases.

Nor does this solution show that said secondary air flow can be controlled, guaranteeing the complete combustion of the material effectively and efficiently.

DESCRIPTION OF THE INVENTION

In view of the foregoing, the present invention relates to a vertical solid fuel boiler.

The boiler comprises a home in which the solid fuel is introduced in the opposite direction to an upward primary air flow. This allows a uniform solid fuel bed to be configured, while accelerating its reaction process.

The primary air flow, once introduced into the home through its lower part, crosses a grill arranged at the lower end of the home. The grill supports the solid fuel bed on an ashtray where the ashes produced by the combustion of the solid fuel are going to stop, while the gases generated ascend through the home and reach their complete combustion when mixed with a secondary air flow that It is introduced into the home.

On the other hand, the upper end of the home has fluid communication with a heat exchanger system, where the energy content of the combustion exhaust gases is used.

The home is divided into two sections. A lower section, where a partial combustion of the solid fuel is achieved, and an upper section, where, thanks to the introduction of the secondary air flow, the combustion of the gases generated in the lower section is completed.

The lower section of the home starts from the upper face of the grill increasing its cross section in the form of a first inverted cone, followed by a first straight section, whose diameter is equal to the largest diameter of the first inverted cone, and terminated in a conical section .

In contrast, the upper section starts from a second inverted cone with a smaller diameter equal to or smaller than the smaller diameter of the conical section of the lower section, followed by a second straight section, whose diameter is equal to the larger diameter of the second inverted cone.

Between the lower section and the upper section of the home there is a narrowing in the form of a third straight section, whose diameter is equal to or smaller than the smaller diameter of the conical section of the lower section.

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This novel structural configuration of the home achieves that in its lower section solid fuel accumulates by copying the geometry of the inner wall of the first inverted cone, allowing the position of the flame front to be regulated, that is, the combustion reaction area is positioned at different height, depending on the power required to the boiler.

Also, the narrowing arranged between both sections of the home, allows to increase the speed of the flow of the gases generated in the lower section. In this way, when the collision occurs between said gas stream and the secondary air flow, it generates a turbulence that facilitates the mixing of both fluids, the combustion of the gases in the upper section of the home being completed, before be dragged to the heat exchanger system.

Another advantage is that the home and the heat exchanger system have been arranged in separate modules, facilitating the work of access of the equipment to the boiler rooms, as well as, achieving the compaction of the boiler, reducing its dimensions and allowing its modular assembly .

DESCRIPTION OF THE FIGURES

The present specification is complemented by a set of figures, illustrative of the preferred example and never limiting of the invention.

Figure 1 represents a top view of the vertical solid fuel boiler.

Figure 2 represents a front view in section AA of Figure 1, showing the home and the ashtray.

Figure 3 represents a side view in section BB of Figure 1, where the home is shown in fluid communication with the heat exchanger system.

Figure 4 represents a rear view in section CC of Figure 1, showing the heat exchanger system, specifically, the tubular heat exchanger.

DETAILED EXHIBITION OF THE INVENTION

The present invention is a vertical solid fuel boiler for use in heating systems, domestic hot water, etc.

As can be seen in figure 1, the boiler comprises a home (1) whose upper end has fluid communication with a heat exchanger system (6), where the energy content of the combustion exhaust gases is used for use in the systems described above.

As Figure 2 shows, the feeding of solid fuel (2) to the boiler, for example, pelletized biomass in the form of pellets, part of a fuel tank (16) included in the boiler itself.

The loading of said fuel tank (16) can be carried out manually, through the emptying of solid fuel bags (2), or automatically, through the discharge of the fuel from another tank of greater dimensions by means of a symph system or a pneumatic system (not seen in the figures).

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To detect the need to fill the fuel tank (16), a sensor (not seen in the figures) can be placed inside it that provides visual and / or audible indications when the amount of solid fuel (2) available in said tank is less than a preset value.

The solid fuel (2) is introduced into the home (1) in the opposite direction to an upward primary air flow (3) that penetrates into said home (1) from its bottom. The primary air flow (3) is driven by the fan (17) arranged below the home (1).

As can be seen in figures 2 and 3, the home (1) is divided into two sections (1.1, 1.2). A lower section (1.1), where a partial combustion of solid fuel (2) is achieved, and an upper section (1.2), where, by the introduction of a secondary air flow (7), the combustion of the gases generated in the lower section (1.1).

In the lower section (1.1) is where the solid fuel bed (2) supported by a grill (4) is formed, which is arranged at the lower end of the home (1). The grill (4) is crossed by the primary air flow (3).

In other embodiments, the primary air flow (3) may be comprised of recirculated combustion gases from the bypass (13) disposed in the outlet duct (20) of the exhaust gases, or a mixture of air and recirculated combustion gases.

The grill (4) is arranged on an ashtray (5), the latter will stop the ashes produced by the combustion of solid fuel (2), while the gases produced by combustion rise through the home (1).

In this sense, the solid fuel (2) is retained on the grill (4) until its conversion to ashes, preventing the boiler from decreasing due to the loss of solid fuel (2).

Preferably, the grill (4) develops a circular motion, which allows to avoid the accumulation of ashes on it, while homogenizing the solid fuel bed (2).

Likewise, it is preferred that under the grill (4) there is an auger screw (10) that allows the evacuation of the ashes towards the ashtray (5).

The lower section (1.1) of the home (1) starts from the upper side of the grill (4) increasing its cross section in the form of a first inverted cone (1.1.1).

Precisely, the solid fuel bed (2) is formed in the limited space between the upper face of the grill (4) and said first inverted cone (1.1.1) of the lower section (1.1) of the home (1), which allows the combustion reaction area to be positioned at a different height depending on the power generated, the latter conditioned by the primary air flow (3) that passes through said fuel bed.

Following the first inverted cone (1.1.1), a first straight section (1.1.2) is provided whose diameter is equal to the largest diameter of the first inverted cone (1.1.1).

Said first straight section (1.1.2) helps to homogeneously shape the solid fuel bed (2), hence the need for the solid fuel supply (2) to be carried out as centrally as possible in the home (1) .

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The lower section (1.1) of the home (1) ends in a conical section (1.1.3) arranged next to said first straight section (1.1.2).

Preferably, the entry of solid fuel (2) into the home (1) is carried out through a dispenser (11) arranged in fluid communication with the conical section (1.1.3) of the lower section (1.1).

Because the boiler is working in depression and it is of interest that the primary air flow (3) passes through the solid fuel bed (2), the solid fuel inlet (2) must be sealed at the passage of said air flow. For this, it is preferred that the dispenser (11) is provided with a rotary valve (12) of the alveolar type.

Following the conical section (1.1.3), that is, between the lower section (1.1) and the upper section

(1.2) of the home (1), a narrowing is arranged in the form of a third straight section (1.3), whose diameter is equal to or smaller than the smaller diameter of the conical section (1.1.3) of the lower section (1.1).

Preferably, the secondary air flow (7) is provided through said third straight section

(1.3).

Likewise, it is preferred that a volute-shaped carving (not shown in the figures) is arranged on the inner wall of the third straight section (1.3) which accelerates and favors the mixing between the gases generated in the lower section (1.1) and the secondary air flow (7), by creating turbulence between both fluids by means of a spiral movement.

Preferably, the secondary air flow (7) is regulated as a function of the amount of oxygen in the exhaust gases. For this, a lambda probe (8) can be used, arranged next to the exhaust duct (20) of the exhaust gases, which measures the oxygen concentration and acts on the speed of a fan (9) that injects the flow of secondary air (7) in the home (1).

On the other hand, the upper section (1.2) of the home (1) part of a second inverted cone (1.2.1) with a smaller diameter equal to or smaller than the smaller diameter of the conical section (1.1.3) of the lower section ( 1.1), followed by a second straight section (1.2.2), whose diameter is equal to the largest diameter of the second inverted cone (1.2.1).

The geometry and volume of the upper section (1.2) of the home (1), guarantees the complete mixing of the gases generated in the lower section (1.1) with the secondary air flow (7), achieving a total combustion of the gases generated in said lower section (1.1), before exiting the heat exchanger system (6).

Preferably, the lower section (1.1), the upper section (1.2) and the third straight section (1.3) of the home (1) are coated with a refractory material (19).

The refractory material (19) used, especially in the upper section (1.2) of the home (1), must allow maintaining a high temperature inside the home (1) to achieve the complete elimination of the dragged particles during the combustion carried out in the lower section (1.1) of the home (1).

Similarly, it is preferred that the lower section (1.1), the upper section (1.2) and the third straight section (1.3) of the home (1) be wrapped in a water jacket (14) that minimizes the thermal losses of the combustion gases.

For its part, preferably, the heat exchanger system (6) comprises, arranged in series, a cascade heat exchanger (6.1) followed by a tubular heat exchanger (6.2).

The cascade heat exchanger (6.1) collects a high percentage of the power and limits the dragging of particles, contained in the combustion gases, towards the tubular exchanger (6.2). The geometry of the cascaded heat exchanger (6.1) helps these particles collide with the walls of the exchanger and decant towards an ashtray (6.1.1), arranged in its lower part.

Preferably, the ashtray (6.1.1) of the cascade heat exchanger (6.1) is covered by a water jacket (6.1.2).

15 Water jackets, both around the components of the home (1) and the ashtray (6.1.1) of the cascaded heat exchanger (6.1), prevent radiation losses of said elements and act as inertia systems.

As for the tubular heat exchanger (6.2), it has three smoke steps to maximize its heat transfer performance, in addition to an automatic cleaning system (18).

Preferably, at the outlet of the tubular heat exchanger (6.2), after the lambda probe (8), at least one extractor fan (15) is provided which guarantees the circulation of combustion gases through the home (1) and the heat exchanger system (6).

Claims (15)

5 10 fifteen twenty 25 30 35 40 Four. Five fifty 1. - Vertical solid fuel boiler comprising a household (1), in which the solid fuel (2) is introduced in the opposite direction to an ascending primary air flow (3) that penetrates said household (1) by its lower part, said primary air flow (3) crosses a grill (4) arranged at the lower end of the home (1), the grill (4) supports a bed of solid fuel (2) on an ashtray (5), the solid fuel combustion gases (2) rise through the home (1) and mix with a secondary air flow (7) that is introduced into the home (1), the upper end of the home (1) has communication fluid with a heat exchanger system (6), where the energy content of the combustion exhaust gases is used, characterized in that the home (1) is divided into two sections, a lower section (1.1), where a partial combustion of solid fuel (2) is achieved, and an upper section (1.2), where the combustion of the gases generated in the lower section is completed (1.1); said lower section (1.1) starts from the upper face of the grill (4) increasing its cross section in the form of a first inverted cone (1.1.1), followed by a first straight section (1.1.2) whose diameter is equal to major diameter of the first inverted cone (1.1.1), and finished in a conical section (1.1.3); the upper section (1.2) part of a second inverted cone (1.2.1) with a smaller diameter equal to or smaller than the smaller diameter of the conical section (1.1.3) of the lower section (1.1), followed by a second straight section (1.2.2), whose diameter is equal to the largest diameter of the second inverted cone (1.2.1); between the lower section (1.1) and the upper section (1.2) of the home (1) a narrowing is arranged in the form of a third straight section (1.3), whose diameter is equal to or smaller than the smaller diameter of the conical section (1.1. 3) of the lower section (1.1). 2. - Vertical solid fuel boiler according to claim 1 in which the secondary air flow (7) is provided through the third straight section (1.3). 3. - Vertical solid fuel boiler according to claim 2 wherein in the inner wall of the third straight section (1.3) a scroll-shaped carving is arranged which accelerates and favors the mixing between the gases generated in the lower section (1.1 ) and secondary air flow (7), by spiral movement. 4. - Vertical solid fuel boiler according to claim 2 wherein the secondary air flow (7) is regulated by a lambda probe (8), which acts on the speed of a fan (9) that injects the air flow secondary (7) in the home (1), according to the concentration of oxygen measured in the exhaust gases. 5. - Vertical solid fuel boiler according to claim 1 in which the grill (4) develops a circular motion, which prevents the accumulation of ashes on it, as well as homogenizing the bed. 6. - Vertical solid fuel boiler according to claims 1 or 5 wherein a screw screw (10) is arranged under the grill (10) that allows the evacuation of the ashes towards the ashtray (5). 7. - Vertical solid fuel boiler according to claim 1 wherein the solid fuel (2) is introduced into the home (1) through a dispenser (11) arranged in fluid communication with the conical section (1.1.3) of the lower section (1.1). 8. - Vertical solid fuel boiler according to claim 7 wherein the dispenser (11) is provided with a rotary valve (12). 5 10 fifteen twenty 25 9. - Vertical solid fuel boiler according to claim 1 wherein the lower section (1.1), the upper section (1.2) and the third straight section (1.3) of the home (1) are covered with a refractory material (19). 10. - Vertical solid fuel boiler according to claims 1 or 9 wherein the lower section (1.1), the upper section (1.2) and the third straight section (1.3) of the home (1) are wrapped in a water jacket (14) that minimizes thermal losses of combustion gases. 11. - Vertical solid fuel boiler according to claim 1 wherein the heat exchanger system (6) comprises, arranged in series, a cascade heat exchanger (6.1) followed by a tubular heat exchanger (6.2). 12. - Vertical solid fuel boiler according to claim 11 wherein the cascade heat exchanger (6.1) includes in its lower part an ashtray (6.1.1), wherein the particles entrained in the combustion gases decant. 13. - Vertical solid fuel boiler according to claim 12 wherein the ashtray (6.1.1) of the cascade heat exchanger (6.1) is covered by a water jacket (6.1.2). 14. - Vertical solid fuel boiler according to claims 4 and 11 wherein at the outlet of the tubular heat exchanger (6.2), after the lambda probe (8), at least one exhaust fan (15) is provided which guarantees the circulation of combustion gases through the home (1) and the heat exchanger system (6). 15.-Vertical solid fuel boiler according to claim 1 wherein the solid fuel (2) used is biomass.