Device for regulating the combustion air flow rate

Abstract

The invention relates to a device for regulating the combustion air flow rate in a wall-mounted, closed-chamber boiler in which there is a flue gas burner and the air enters the chamber through a suitable supply line (2) penetrating therein. A flue gas line (3) for discharging combustion products is also connected to the chamber. The two lines (2, 3) are routed separately or axially. The device comprises at least one element for increasing the air flow rate of the supply line (2) in order to vary the air flow rate of the air flowing into the closed chamber. This increasing element is formed by a movable member (10) actuated from the outside of the supply line (2) and can be locked in the position in which it increases the flow rate of the supply line again actuated from the outside of the supply line (2).

Description

The invention relates to a device for regulating the flow rate of combustion air in a wall-mounted, closed-chamber boiler, in which a conventional burner is installed, and the air enters the chamber through a suitable supply line leading to it. A flue gas discharge line is connected to the chamber, and the two lines are routed separately or coaxially. The device comprises at least one element for throttling the air-passing cross-section of the supply line, in order to change the flow rate of air entering the closed chamber. As is well known, a boiler of this type has a closed chamber containing a burner. At least two pipes lead to the burner, namely a supply pipe for combustion air and another pipe for the discharge of flue gas or combustion products. These pipes, depending on their length, may be coaxial (the flue gas pipe inside the air supply pipe) or may be run separately. In particular, but not limited to, a boiler with separate pipes has a draft regulator in the supply pipe in the known manner, which allows the combustion air flow rate to be varied and thus the ratio of the combustion air quantity to the gas quantity in the burner to be regulated, so that the presence of NOX and CO in the flue gas leaving the boiler is limited. As an example: the optimal air / gas ratio is approx. 10 m3 air / 1 m3 natural gas. This ratio can be controlled by the aforementioned draft controls. However, this requires the following operations: measuring the “composition” of the flue gas (i.e. the CO2, NOX and CO content); removing the air duct; changing the position of the draft control or draft controls in the duct; fixing the duct to the closed chamber; measuring the flue gas composition again and, if necessary, repeating the operations of removing the air duct, adjusting the draft control and fixing the duct. This obviously takes a lot of time, and it is difficult to control the flow rate in the duct. This is therefore very expensive. Another solution to modify the air flow rate instead of using draft controls is to control the speed of a conventional fan in a closed chamber. However, this requires quite complex and expensive electronic devices. The object of our invention is to provide an improved device for controlling the flow rate of air flowing into a closed chamber of a boiler. The object of our invention is, in particular, to provide a device of the above type in which the adjustment can be made in the air supply line without the need to disconnect the line from the chamber. Another task is to design a device with a simple construction and that can be easily attached to a closed chamber boiler. These objects are achieved according to the invention in that the throttling element is formed by a member which is operable and movable from outside the supply line, which is lockable in the position in which it throttles the flow cross-section of the supply line, again operated from outside the supply line, and the movable member is arranged at the end of the supply line connecting to the closed chamber of the boiler. Our invention is described in connection with its exemplary embodiments with the help of our drawings, of which the Figure 1 is a perspective view of a boiler equipped with the device according to the invention, Figure 2 shows a device according to the invention, A partially exploded perspective view of the air supply line of the boiler shown in Figure 1, Figure 3 is an exploded perspective view of the conduit of Figure 2, viewed from below. The boiler 1 shown in the figures comprises a conventional closed chamber containing a gas burner (not shown in the drawing) inside. Two separately routed pipes are connected to the chamber. One of the pipes is the supply pipe 2 for the air required for combustion, and the other is the flue gas pipe 3 for the exhaust of flue gases or combustion products. The end of the supply line 2 is introduced directly into the closed chamber forming the interior of the boiler 1. An opening 6 is formed at the end 5 of the supply line 2, which is partially closed by the empty, spherical cap part 7. In this way, the opening 6 of the end 5 of the supply line 2 is essentially in a plane which is not perpendicular to the longitudinal axis K of the supply line 2, but is on one side thereof. The form-fitting member 10 is fixed to the line end 5, which has a shape which - preferably by form-fitting - fits the line end 5. Consequently, this form-fitting member 10 is also preferably designed as an article of a spherical cap and has a surface opening 11 therein, the dimensions of which are preferably equal to the dimensions of the end opening 6 of the supply line 2. The form-fitting member 10 has an end flange 13 which - when the member 10 is fitted to the supply line 2 - rests on the upper housing part 14 of the housing 15 of the boiler 1 and, after being sufficiently positioned relative to the end opening 6 of the supply line 2, is secured to the housing part 14. The specific shape of the form-fitting member 10 allows the end opening 6 of the supply line 2 to be changed as desired. In this way, the correct (quantitative) supply of combustion air can be selected based on the measurement of the composition of the flue gas leaving the boiler. The invention is used as follows: with the boiler installed and in operation, an operator, using known equipment, measures in a known manner the composition of the flue gas leaving the closed chamber through the flue gas line 3. If this flue gas contains a high proportion of CO2 (and CO), the operator adjusts the end flange 13 by rotating it in the direction of the arrows F shown in Figure 2. As a result of this movement, the form-fitting member 10 also rotates around the supply line 2, thereby changing the position of the end opening 6 of the supply line 2 relative to the opening 11 of the form-fitting member 10. In the illustrated embodiment, the purpose of this change is to reduce the degree of throttling of the end opening 6 by the form-fitting member 10, and thus to increase the useful cross-section for the inflow of combustion air into the closed chamber. This increases the air flow rate in the burner and, as a result, reduces the CO2 content of the flue gas. After determining the optimal position of the form-fitting member 10 relative to the wire end 5 of the power line 2, HU 222 359 Bl stake, the form-fitting member 10 is secured in this position with conventional, not shown, screws which cooperate with the end flange 13 and the housing part 14 of the housing 15 of the boiler 1. The invention enables easy regulation of the air flow rate to the burner with a solution that is simple in principle and construction. The regulation does not require the removal of the supply line 2 from the boiler 1 and can be regulated from outside this line. A preferred embodiment of the invention has been described in which the device according to the invention comprises not only the member 10, but also the end of the air supply line 5 has a special shape. This special shape of the line and the form-fitting member 10 allows for a suitable direction of the air into the closed chamber. In one modified embodiment, not shown, however, the supply line 2 may be of the usual type, completely cylindrical, and its end opening 6 is in a plane perpendicular to the axis K. In this case, the throttle member may be a movable closing device acting perpendicular to this axis or a venting type valve. According to a further variant, the throttle member is formed by two flat, circular bodies placed one on top of the other. These bodies have openings separated by solid parts, which can be completely or partially overlapped in order to increase or decrease the useful cross-section for the combustion air flow. These solutions are also within the scope of the invention. We have described a solution that can be used in the case of a supply line that is separate from the flue gas line. The invention can also be used in the case where these lines are coaxial and the air flow cross-section is a ring surrounding the flue gas line. In this case, the throttle member can be formed, for example, by a vent type element or by two flat, annular bodies, the openings of which can be overlapped or separated in the manner described above.

Claims

PATENT CLAIMS 1. Device for controlling the flow rate of combustion air in a wall-mounted, closed-chamber boiler (1), in which there is a conventional burner, and the air enters the chamber through a supply line (2) that enters at the end opening (6); a flue gas line (3) for discharging combustion products is connected to the chamber, and the two lines (2, 3) are routed separately or coaxially; the device comprises at least one element for throttling the air-passing cross-section of the supply line (2) to change the flow rate of air flowing into the closed chamber, characterized in that the throttling element is formed by a form-fitting member (10) operable and movable from outside the supply line (2), which is lockable in the position in which the flow-through cross-section of the supply line (2) is throttled by actuation from outside the supply line (2), and the movable form-fitting member (10) is arranged at the line end (5) of the supply line (2) connected to the closed chamber of the boiler (1).

2. Device according to claim 1, characterized in that the throttle element is formed by a form-fitting member (10) formed as at least a part of a substantially spherical cap, the surface of which has an opening (11); the form-fitting member (10) is movably arranged on the line end (5) of the air supply line (2), and this line end (5) is also formed as at least a part of a spherical cap and is provided with a surface end opening (6) which is located essentially in an inclined plane with respect to the longitudinal axis (K) of the supply line (2).

3. Device according to claim 2, characterized in that the body of the throttle element is provided with an end flange (13) projecting perpendicularly to the supply line (2) for rotating the form-fitting member (10) relative to the supply line (2), and the form-fitting member (10) is designed to be lockable with fastening elements after rotation.

4. The device according to claim 1, characterized in that the throttling element is a venting type member.