EP1091171B1 - Method for the generation of a homogeneous air flow in a forced-draft burner and device for its realization - Google Patents

Abstract

The method involves altering the structure of the air flow channel. The air flow is generated by an impeller (3) of a fan (1) in a spiral channel of the fan casing and then conducted in a perpendicular deflector into a burner casing (8) at the side, to flow through air holes into a distributor element (13) in the burning zone of the fan burner. There is an n-stage reduction of the degree of turbulence, where n is at least 2 and preferably equals 2. A first stage of the reduction at the deflector is a linear baffle (14), preferably in the form of a lamella grating. An optional second stage of the reduction is a tube baffle (22), preferably in the form of an open cylinder grating (23) open at the end to the distributor element. An optional third stage of the reduction is a circular baffle in the form a grating with small holes, which homogenises the air flow in front of the distributor element. An Independent claim is included for a device for implementing the method.

Description

The invention relates to a method according to the preamble of claim 1 and Device for performing such a process on a forced draft burner.

The invention belongs to the field of thermal energy and can be used for the combustion of Gas and oil can be used in forced draft burners in household and industrial equipment.

It is a method of feeding the air flow into the burning zone of forced draft burners known in which the air flow through the radial impeller of a blower into the spiral duct of the blower housing and then pressed approximately at right angles in a laterally arranged Burner housing is deflected, from which it is through air holes in a distributor element flows into the combustion zone of the fuel jet.

US 5 184 949 A shows an oil burner with a pistol-shaped burner housing. The combustion air delivered by the blower becomes tangentially cylindrical Combustion air duct supplied so that this with a swirl flow the combustion zone reached. In addition, DE 30 24 225 A is a radial fan with a pressure side Flow guidance, which consists of several longitudinally extending guide channels exists, known. It can in the cylindrical mouth of the blower for example, two perforated disks can also be arranged one behind the other.

For the implementation of the method described above, a device is known that a Blower with an electric motor, a radial impeller, a housing with a spiral channel and Contains redirection. The deflection faces the side of the electric motor. The Device also contains a burner, which consists of the following parts: cylinder housing with Side cutout for the connection of the deflection and a rear floor, distributor element with air holes. The air holes are even around a hole in the center arranged, which is intended for the fuel lance. Thanks to the deflection that faces the side of the electric motor, the burner picks up rational space in the free space above the electric motor of the blower, which is essential Reduction in weight and dimensions of the entire device.

The aim of the present invention is to create a homogeneous air flow in the Brenner by changing its structure and creating optimal conditions for the burning process and the improvement of aerodynamic characteristics of the Blower by increasing consumption and pressure as well as efficiency.

According to the invention, this aim is achieved by the application of those mentioned in claim 1 Measures achieved. Additional details are set out in claims 2 to 5 remove. The device for performing the method according to the invention has the features mentioned in claim 6. Claims 7 to 22 contain further Features of such a device.

Homogenization is achieved by reducing the degree of turbulence at least in two stages of the airflow reached. The 1st stage on the deflection as a linear calming device, preferably in the form of a lamellar grid, the 2nd stage in the burner housing as Pipe calmer in the form of a cylinder grille with one leading to the distributor element Output cross-section and the 3rd stage in the form of a circular calmer directly in front of the distributor element be arranged.

für die 1. Stufe:

M₁ : M = (1÷3) : (1÷15), vorzugsweise M₁ : M = 1 : 10;

ΣF₁ : ΣF = 1÷8, vorzugsweise ΣF₁ : ΣF = 4;

für die 2. Stufe:

M₂ : M = (1÷3) : (1÷15), vorzugsweise M₂ : M = 1 : 10;

ΣF₂ : ΣF = 3÷12, vorzugsweise ΣF₂ : ΣF = 6;

M bedeutet Maximalmaß des Turbulenzgrades am Eingang in die 1. Stufe; M₁ und M₂ bedeuten Maximalmaß der Turbulenzengrade an den Ausgängen aus der 1. Stufe bzw. 2. Stufe; ΣF bedeutet Summenfläche der Luftlöcher des Verteilerelementes; ΣF₁ und ∑F₂ sind Summenflächen der Durchgangsquerschnitte der Gitter von Beruhigem der 1. Stufe bzw. 2. Stufe.

The 2-stage reduction in the degree of turbulence in the air flow is already achieved if the following geometric conditions are met:

for the 1st stage:

M ₁ : M = (1 ÷ 3): (1 ÷ 15), preferably M ₁ : M = 1: 10;

ΣF ₁ : ΣF = 1 ÷ 8, preferably ΣF ₁ : ΣF = 4;

for the 2nd stage:

M ₂ : M = (1 ÷ 3): (1 ÷ 15), preferably M ₂ : M = 1: 10;

ΣF ₂ : ΣF = 3 ÷ 12, preferably ΣF ₂ : ΣF = 6;

M means maximum degree of turbulence at the entrance to the 1st stage; M ₁ and M ₂ mean the maximum degree of turbulence at the outputs from the 1st stage and 2nd stage; ΣF means total area of the air holes of the distributor element; ΣF ₁ and ∑F ₂ are total areas of the passage cross-sections of the gratings of the 1st and 2nd stage.

If a deeper structural redesign of the flow of the air flow is necessary, realized an n-stage reduction in the degree of turbulence, where N> 2, d. H. three-stage or multi-stage reduction. In addition, one leads into the air flow behind the cylinder grille of the pipe calmer in front of the distributor element one or more circular calmers with grids, which preferably have round holes of small diameter.

In the proposed method for creating a homogeneous air flow in the forced air burner it is advantageous to add the consumption at the exit from the 1st stage to be regulated by a gate valve.

An additional reduction in the degree of turbulence at the 2nd stage is through a pipe pressure reducer to realize with cylinder grille. This grid is the cylinder grid of the Pipe calmers geometrically similar. The pipe pressure reducer is outside or (preferably) mounted on the inside of the pipe calming device, so that the possibility of disabled turning in the direction of the circle.

The device for implementing the method of creating a homogeneous air flow contains a blower with an electric motor, a radial impeller, a blower housing with a spiral channel and a deflection facing the side of the electric motor. It also has a burner, which consists of the following parts: housing with side cutout for connecting the redirection and with a rear floor with opening in the center for the fuel lance and round distributor element with air holes that evenly a hole is arranged in the center. It is at the exit from the redirection the 1st stage to reduce the degree of turbulence was installed. It is in the form of a Linear calming device with a lamella grid and is preferably made of lamella elements educated.

The second stage for reducing the degree of turbulence is installed inside the burner housing. It is in the form of an axially symmetrical pipe calmer with a cylinder grille executed, and this grid preferably has longitudinal slots.

In addition, there is a third stage in the form of a circular calmer in front of the distributor element as a perforated grid element. In the case of a 2-stage calming, 2 can optionally of the 3 levels can be combined.

The device with the main features and in particular with the entirety of the main and Additional features make it possible to implement the process for creating a homogeneous Air flow by changing its structure and solving the technical issues Task of making a uniform field of speeds of the Airflow in the combustion zone with simultaneous increase in aerodynamic characteristics of the blower such as consumption, pressure and efficiency.

Fig. 1:

In Pos. B: Eine Stimansicht des Gehäuses teilweise im Schnitt,
In Pos. A: Den Schnitt 1-1 aus Fig. 2,
In Pos. A-1 und A-2: Vergrößerte Auszüge aus Pos. A,

Fig. 2:

Den Schnitt 2-2 aus Fig. 1 ohne Elektromotor und Seitenabdeckung,

Fig. 3:

Den Schnitt 3-3 aus Fig. 1 und

Fig. 4:

Einen Teil-Schnitt 2-2 aus Fig. 1

The drawing shows a blower housing with which the method according to the invention for homogenizing the air flow can be achieved. It shows:

Fig. 1:

In Pos. B : A front view of the housing, partly in section,
In Pos. A : Section 1 - 1 from Fig. 2,
In items A-1 and A-2 : enlarged excerpts from item A ,

Fig. 2:

Section 2 - 2 from FIG. 1 without an electric motor and side cover,

Fig. 3:

The section 3 - 3 of Fig. 1 and

Fig. 4:

A partial section 2 - 2 from FIG. 1

The device for implementing the method of creating a homogeneous air flow contains a blower 1 with an electric motor 2, a radial impeller 3, a blower 4 with a spiral channel 5 and a deflection 6, which faces the side of the electric motor 2 and a burner 7 arranged next to it. The latter consists of the following parts: Burner housing 8 with a rectangular side cutout 9 for connecting the deflection 6, floor 10 with opening in the center for the fuel lance 12 and round distributor element 13 with air holes 31 that are even around a hole 32 in the center for the essay 33 of the fuel lance 12 are arranged around.

The bottom 10 and the distributor element 13 can also have other holes for the accommodation the elements of the system of electric ignition, visual observation of the flame etc. (not shown on the pictures.

The linear calming device 14 is arranged at the exit from the deflection 6. It consists of a louvre grille 15, preferably made of individual slats 16, with the wide side are attached along the air flow. The resistance to the coming To reduce airflow, the downstream edge 17 of the fins 16 tapers. Further is the upstream edge 18 profiled according to the radius, with the center that the longitudinal axis 19 of the burner. The slats 16 can be placed that there is a possibility to change the distance between them. The linear reassurer 14 is installed symmetrically to the horizontal axis 20 of the burner. At the exit from the A linear slide valve 14 is provided with a gate valve 20. This is condensed into one Game between the deflection and the side cutout 9 in the burner housing 8 installed and can be moved up / down in guide grooves 21.

Inside the burner housing 8 is the axially symmetrical tube calming device 22 with cylinder lattice 23, which preferably contains longitudinal slots. That's how the louvre grille is 15 of the linear calming device 14 and the cylinder grille 23 of the pipe calming device 22 perpendicular to each other.

The pipe calming device 22 can contain openings of any shape, e.g. B. transverse slotted holes, round or non-round polygonal holes, etc., under the following condition: ΣF ₂ : ΣF = 3 ÷ 12, preferably ΣF ₂ : ΣF = 6.

The condition L ₁ L L ₂ , preferably L ₁ = L ₂ , applies to the length L _{1 of} the cylinder grille 23 of the tube calming device 22, where L _{2 is} the length of the lamellar grating 15 of the linear calming device 14.

The Rohrquuhiger 22 can be made with a closed end section 25, the between the cylinder grid 23 and the distributor element 13.

The pipe calming device 22 can be fixed to the bottom 10 of the burner housing 8, but it can also be attached to the distributor element 13 and with it a removable one Form assembly. It is also possible to constructively design the pipe calming device 22 to be made with the distributor element 13.

If necessary, one pre-assembles behind the cylinder grille 23 of the pipe stabilizer 22 the distributor element at least one additional circular calmer 26 with a grid 27, which preferably has round holes 28 with a small diameter.

To steer the degree of turbulence at the 2nd stage, you mount inside or outside in the Pipe calmer 22 additionally, with the possibility of disabled turning in the circular direction, a pipe pressure reducer 29 with a cylinder lattice 30, the cylinder lattice 23 of the Rohrberuhigers 22 is geometrically similar.

The process for creating a homogeneous air flow in the forced air burner is in that the air flow through the impeller 3 of the blower 1 into the spiral duct 5 of the blower housing 4 pressed and from it in the deflection 6 from the lamella 15 of the Linear calming device 14 is sent where the 1st stage to reduce the degree of turbulence 3 times ÷ 15 times (preferably ten times). It also becomes another important one Correlation between the sum areas of the air holes 31 of the distributor element 13 and the passage cross sections of the lamellar grid 15 are met. It lies in the interval 1.0 ÷ 8.0 and is preferably 4.0.

After the linear calming device 14, the air flow is reduced with several degrees of turbulence sent into the burner housing 8, where it through the slots 24 of the cylinder grid 23 of Rohrberuhigers 22 is let through. This will make the 2nd stage of reduction of the turbulence rod (also 3 times ÷ 15 times, preferably ten times).

The correlation between the sum areas of the air holes of the distributor element 13 and Cross sections of the cylinder lattice 23 in the interval 3.0 ÷ 12.0 (preferably 6.0) is reserved. Compliance with the aforementioned correlation of the levels of turbulence With the 2-stage scheme it is possible to achieve a homogeneous air flow behind the 2nd stage, which greatly increases the efficiency of the burning process.

The fulfillment of the above Correlations of the total areas of the air holes in the distributor element and the grid of the 1st and 2nd stage and / or, if necessary, a 3rd stage the structural redesign of the air flow with practically no internal losses and the Achievement of high aerodynamic characteristics of the whole gas burner device.

Example: There is a forced draft burner with a fan, which is calculated for the air supply to the combustion zone at a height of 97.5 m ³ per hour. The cylindrical burner housing has 90.0 mm inner diameter and 99.0 mm length. In the initial section of the housing there is the distributor element with 8 holes with a diameter of 9.0 mm, which are arranged evenly around the hole in the center for the fuel lance with the attachment (diameter 18.0 mm). It follows that the total area of the passage cross sections of the holes in the distributor is approximately 760 mm ² .

The initial cross-section of the deflection, in which the first stage of the reduction in the degree of turbulence in the form of a lamellar grille of the linear calming device is to be installed, has the dimensions as follows: height 34.0 mm and length 99.0 mm. As a result, the maximum degree of turbulence at the entrance to the 1st stage is 99.0 mm. If the excellent correlation M ₁ : M = 1 10 is used for the 1st stage, the lamella grid should be made up of 10 cells (interval between cells = 9 mm, thickness of the lamella elements = 1.0 mm). As a result, the section of a cell of the lamellar grille of the linear sedative will have the following dimensions: height = 34.0 mm and length = 9.0 mm. In this case the maximum degree of turbulence at the entrance to the 2nd stage will be 34.0 mm.

If you use the excellent correlation M2: M1 = 1:10 for the 2nd stage, you get the characteristic size of the slotted groove of the cylindrical grille of the linear calming device = 3.4 mm; for convenience of execution, it can be rounded down to 3.00 mm.

Let us leave the outer diameter of the linear sedative equal to 74.00 mm. Then would be it expedient, with the same length of the cylindrical grille of the linear calming device and the Length of the lamellar grille of the linear calming device (= 99.0 mm) the grille as follows to be designed: 46 slotted grooves, 3.0 mm wide, distances between them approx. 2.0 mm.

For the above-mentioned geometrical quantities of the 1st and 2nd stages of reducing the degree of turbulence, the correlations of the total areas of the passage cross sections of the grille of the calmers to the total area of the air holes of the distributor will be at optimal intervals and are as follows: for the 1st stage ΣF ₁ : ΣF = 4.0; ΣF ₂ : ΣF = 6.0.

The device for implementing the method of creating a homogeneous air flow acts as follows: The air flow is with the impeller 3 radial type that rotates from the electric motor 2 into the spiral channel 5 of the housing 4 of the blower 1 pressed. From the spiral duct 5, the air flow with the deflection 6 through the louvre grille 15 derived from the linear calming device 14, where the 1st stage of reducing the degree of turbulence is realized and comes into the burner housing 8, where the 2nd stage of Reduction in the degree of turbulence is realized when the airflow through the cylinder grille 23 of the pipe calming device 22 goes. If necessary, a calming circuit follows 26 in the form of a grid 27 provided with small holes 28.

After the pipe calming device 22 in the initial section of the cylinder lattice 23, which is the distributor element 13 is parallel, the air flow is characterized with a high degree of homogeneity. The Homogeneity also remains behind the air holes 31 in the combustion zone of the propellant gas.

Claims (10)

1. A method for creating a homogenous air current by means of a structural change, wherein the air current is pressed into the spiral channel (5) of the fan housing (4) by the impeller (3) of a fan (1) and then conveyed into a laterally arranged burner housing (8) after an approximately perpendicular deflection (6), wherein said air current flows into the burner zone of a fan burner through air holes (31) in a distribution element (13),
   characterized in
   an at least 2-stage reduction of the degree of turbulence, wherein at least two of the following 3 stages are utilized: 1. stage, a linear tranquilizer (14), preferably in the form of a lamellar screen (15), at the deflection (6) from the spiral channel (5) to the burner housing (8); 2. stage, a tubular tranquilizer (22), preferably in the form of a cylindrical screen (23) that is open on the end face pointing to the distribution element (13), in the burner housing (8); 3. stage, a circular tranquilizer (26) in the form of a screen (27) that is provided with small holes (28) and homogenizes the air current upstream of the distribution element (13).
2. The method according to Claim 1,
   characterized in that
   the 2-stage reduction of the degree of turbulence of the air current is realized in accordance with the following geometric conditions:

   for the 1. stage:

   M₁ : M = (1÷3):(1÷15), preferably M₁ : M = 1 : 10;

   ΣF₁ : ΣF = 1÷8, preferably ΣF₁ : ΣF = 4;

   for the 2. stage:

   M₂ : M = (1÷3) : (1÷15), preferably M₂ : M = 1 : 10;

   ΣF₂ : ΣF = 3÷12, preferably ΣF₂ : ΣF = 6;

   wherein M symbolizes the maximum degree of turbulence at the inlet of the 1. stage, M₁ and M₂ respectively symbolize the maximum degrees of turbulence at the outlets of the 1. stage and the 2. stage, ΣF symbolizes the sum of the air hole surfaces of the distribution element and F₁ and ΣF₂ respectively symbolize the sums of the open cross-sectional screen surfaces of the tranquilizers of the 1. stage and the 2. stage.
3. A device for creating a homogenous air current, comprising a fan (1) with an electric motor (2), a radial impeller (3), a fan housing (4) with a spiral channel (5), a deflection (6) that is directed toward the side of the electric motor and a burner housing (8) with a lateral cutout (9) for connecting the deflection (6), a rear bottom (10) with a central opening (11) for a fuel lance (12) and an oppositely arranged distribution element (13) in the form of a disk provided with air holes (31),
   characterized in that
   at least two of the following 3 stages are installed at the deflection (6) in order to realize the at least 2-stage reduction of the degree of turbulence: 1. stage, a linear tranquilizer (14), preferably in the form of a lamellar screen (15); 2. stage, an axially symmetrically mounted tubular tranquilizer (22) in the form of a cylindrical screen (23) with slots (24) that preferably extend longitudinally in the burner housing (8); 3. stage, a circular tranquilizer (26) in the form of a screen (27) with small holes (28) upstream of the distribution element (13).
4. The device according to Claim 3,
   characterized in that
   the cylindrical screen (23) of the tubular tranquilizer (22) has openings of arbitrary shape which fulfill the following condition:

   M'₂ : M₁ = (1÷3): (1÷15), preferably M'₂ : M₁ = 1 : 10 ;

   ΣF'₂ : ΣF = 3÷12, preferably ΣF'₂ : ΣF = 6;

   wherein M'₂ symbolizes the maximum size of a hole and ΣF'₂ symbolizes the sum of the open cross-sectional hole surfaces.
5. The device according to Claim 3,
   characterized in that
   the cylindrical screen (23) of the tubular tranquilizer (22) has a closed end section (25).
6. The device according to Claim 3,
   characterized in that
   the cylindrical screen (23) of the tubular tranquilizer (22) is stationarily mounted on the bottom (10) of the burner housing (8).
7. The device according to Claim 3,
   characterized in that
   the cylindrical screen (23) of the tubular tranquilizer (22) is mounted on the distribution element (13) and forms a removable unit together with said distribution element.
8. The device according to Claim 3,
   characterized in that
   the cylindrical screen (23) of the tubular tranquilizer (22) and the distribution element (13) form a collectively fabricated unit.
9. The device according to Claim 3,
   characterized in that
   a screen-like tubular pressure reducer (29) is additionally arranged in the cylindrical screen (23) of the tubular tranquilizer (22), wherein said pressure reducer is realized geometrically similar to the cylindrical screen (23) of the tubular tranquilizer (22).
10. The device according to Claim 9,
    characterized in that
    the tubular pressure reducer (29) is arranged outside the tubular tranquilizer (22).

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