RU2754480C1 - Solid-fuel heater with three-zone combustion air supply - Google Patents

Abstract

FIELD: heating.

SUBSTANCE: invention relates to a solid-fuel heater with a three-zone combustion air supply, especially to boilers with wood gasification. A solid-fuel heater with a three-zone combustion air supply, including a lower outlet (16) for the lower primary air, an upper outlet (11) for the upper primary air, an outlet (12) and an inlet (14.3) for the secondary air, wherein the secondary air is passed between the inlet (14.3) and the outlet (12) in a separate vent (9), further including a first inlet (14.1) for the lower primary air and a second inlet (14.2) for the upper primary air, wherein the lower primary air is passed between the first inlet (14.1) and the lower outlet (16), is passed in a separate vent (10), and the upper primary air between the second inlet (14.2) and the lower outlet (11) is passed in a separate vent (3), characterised by the fact that a valve (13) is connected to each inlet (14.1, 14.2 and 14.3), each of the valves (13) is installed on a boom (7), wherein all three booms (7) are fixed to the shaft (8) and wherein the inlets (14.1, 14.2 and 14.3) are equipped with a common movable gate (5). The movable gate includes two control holes (15).

EFFECT: invention provides a possibility to effectively adapt to types of fuel with varying properties.

3 cl, 6 dwg

Description

Technology area

The technical solution concerns a solid fuel heater with a three-zone combustion air supply, in particular for boilers with gasification of wood.

Current state of technology

The most advanced solid fuel heaters, especially wood gasification boilers, are equipped with a three-zone (or three-stage) combustion air supply - secondary air, bottom primary air and top primary air. Secondary air is fed to the flame at the nozzle (the hole that connects the upper fuel space and the lower combustion space). It provides combustion of flammable gaseous components of the flame - secondary combustion. Bottom primary air is fed into the burning fuel bed at the bottom of the fuel space. It provides a change from solid fuel to gaseous components - primary combustion (or gasification) in the lower layer of the fuel. It also determines the performance of the heater. Top primary air is supplied above the fuel bed at the top of the fuel space. It maintains the intensity of the primary combustion - it causes the build-up of a hot layer. It allows the combustion of poorly burning fuels (large fragments, soft or damp wood). Speeds up the kindling. It is sometimes referred to as pre-drying air.

Secondary air is usually supplied through a separate vent (a system of pipelines, channels and cavities), at its inlet there is a control element (valve), which is manually controlled, in more complex versions - using an electric drive controlled by the boiler regulator based on a signal from a lambda probe ...

The upper primary air and the lower primary air are usually supplied through one common outlet (primary air), at its inlet there is also a control element (valve), which is controlled manually or by means of an electric actuator controlled by the boiler regulator based on the power requirements (signal from the flue gas sensors and water temperature). This common vent is subsequently divided into an upper primary air vent and a lower primary air vent. Typically, the design is as follows: The general vent (primary air) is led out of the casing of refractory metal sheets, which are equipped with the side walls of the fuel space. A portion of the primary air then behind this skin moves upward as the upper primary air, and a portion of the primary air behind this skin moves downward as the lower primary air. The said refractory lining then has openings in its lower part through which the lower primary air flows into the fuel space, and openings in their upper part through which upper primary air enters the fuel space. The area ratio of the top and bottom openings determines the relationship between the top and bottom primary air. This ratio has been selected to match the most commonly used fuels. Typically, this value is approximately 2: 1 in favor of the lower primary air. The fact that the mentioned ratio is constant is a disadvantage for the combustion of fuels with different parameters. For example, for fuels that are easy to ignite (dry and small fragments such as wood chips, branches and cuttings), the standard amount of top primary air causes unwanted combustion of the fuel throughout the entire fuel space. This reduces the quality of combustion, controllability, efficiency. The opposite situation occurs with fuels that are difficult to ignite (wetter wood or large fragments). In such a situation, there is a lack of upper primary air, combustion occurs with a large excess of air, with a lower power, with a lower efficiency and quality of combustion.

From the Chinese document CN 204005952 U, equipment for the combustion of pellets is known, including the supply of combustion air, inlets and outlets of primary, secondary and tertiary air, whereby the primary air, as well as secondary and tertiary air are supplied in a separate pipeline or vent.

Existing heaters, in particular boilers with gasification, for the reasons given do not allow to effectively adapt to fuels of different properties, in particular, wetter fuel or large fragments on the one hand, and finer and dry fuel (chips) on the other hand.

The essence of the technical solution:

The disadvantages of the known equipment are eliminated by a solid fuel heater with a three-zone supply of combustion air in accordance with the technical solution, including a lower outlet of the lower primary air, an upper outlet of the upper primary air, a secondary outlet and a secondary inlet of secondary air, moreover, the secondary air between the secondary inlet hole and secondary outlet are fed in a separate outlet (route). The heater also includes two separate vents (routes) from the inlet to the outlet of the bottom and top primary air entering the combustion space. These separate vents are designed in such a way that they include a first inlet of the lower primary air and a second inlet of the upper primary air, wherein the lower primary air between the first inlet and the lower outlet passes in a separate vent of the lower primary air and the upper primary air between the second inlet and upper outlet pass through a separate upper primary air vent. The essence of the technical solution lies in the fact that a valve mounted on the boom is connected to each inlet of the primary air and secondary air drive, moreover, the boom is fixed on the shaft, and, moreover, the inlets are equipped with a common movable flap.

In accordance with a first advantageous embodiment of the technical solution, the inlets for supplying primary air and secondary air are located on a distributor, which is located on the outside of the heater, moreover, the shaft on which the booms are fixed is located outside the distributor.

An advantageous solution is to control a movable damper with two control holes by adjusting the amount of primary air and secondary air that enters the inlet openings.

The advantage of the technical solution is that it allows in a simple way - by moving the shutter 5 to set any required ratio of all three types of air (secondary, upper primary and lower primary), as well as optimally adapt the heater for efficient combustion of various types of fuel and the instantaneous state of combustion. To control the air ratio, a single electric drive is sufficient, while the solution of existing boilers requires two electric drives. Another advantage is therefore also simplicity, resulting in lower cost and higher reliability.

Overview of Drawings in Drawings

RICE. 1 schematic illustration of a heater in the foreground

RICE. 2 section A-A of the heater from Fig. 1

RICE. 3 is a schematic perspective (3D) view of the air distributor, where the control flap is not shown for clarity.

RICE. 4 is a schematic front view of an air distributor with a damper in a position with a balanced supply of secondary air and lower primary air when burning conventional fuel, which burns as standard (eg dry logs).

RICE. 5 is a schematic front view of an air distributor with a damper in the position with maximum secondary air supply when burning easily burning fuel (eg dry wood chips).

RICE. 6 front view of the air distributor with the damper in the position with the maximum supply of the upper primary air when burning poorly burning fuel (eg wet or large logs).

Execution example

On the example of the execution of the technical solution shown in Fig. 1, there is a heater 100, a gasification boiler for the manual application of wood, with a fuel space 1 in the upper part and an afterburner space 17 in the lower part. On the front wall of the heater 100 is a parallelepiped combustion air distributor 4 that includes three mutually separated chambers. Each of these chambers has circular inlets in the front wall for supplying combustion air, the first inlet 14.1 of which is for the lower primary air, the second inlet 14.2 is for the upper primary air and the inlet 14.3 is for the secondary air. ... The inlets 14.1, 14.2 and 14.3 are equipped on their inner side with round valves 13, each of them is attached to a curved boom 7, All three booms 7 are fixedly connected to a shaft 8 located outside of the distributor 4. The shaft 8 is movably located at both ends in a paired arrangement 6. The geometry of the booms 7 is chosen so that the common center of gravity of the booms 7 and valves 13 in all operating positions, ie, from "closed" to "fully open", is to the right of the pivot axis of the shaft 8, so that the valves 13 are located in a quiet position under the influence of gravity in a closed state. On the front surface of the distributor 4 there is a rectangular, in the horizontal direction, a movable damper 5 (the movable damper 5 is indicated by a shaded area) with a pair of rectangular adjustment holes 15. The damper 5 also includes an oblong central gap 18 located horizontally in the center of the damper 5, which allows the passage of arrows 7 and provides the minimum size of the limitation of the surface of the inlet openings 14.1 14.2 14.3. Flap 5 ensures the achievement of the required air ratio for all kinds of operating conditions (ignition, combustion, afterburning) and all kinds of fuel (good burning, standard and poor burning).

To the left chamber of the distributor 4 in the lower wall is attached the pipeline of the lower outlet 10 of the lower primary air, which is discharged into the lower outlet 16. To the central chamber of the distributor 4 in the lower wall is attached the pipeline of the secondary outlet 9 of the secondary air, which is discharged into the outlet 12 formed by the outlet nozzle secondary air. To the right chamber of the distributor 4 in the upper wall is connected the pipeline of the upper outlet 3 of the primary air, which is discharged into the upper outlet 11 of the outlet of the upper primary air.

Other versions of the technical solution are also possible, the distributor 4 may not be a separate unit, it can be integrated into the boiler structure, for example, so that the boiler structure forms the rear wall of the distributor 4, etc. The individual chambers of the valve 4 may have a different order than that indicated in the example of execution. Damper 5 may not be movable, but, for example, rotary. The shape and number of adjusting holes 15 of the shutter 5, etc. may be different.

The function of the heater 100 is as follows: In the inlets 14.1, 14.2, and 14.3 of the distributor 4, combustion air flows, eg by means of a flue gas fan. Under the pressure of air, the valves 13 with arrows 7 are inclined towards the inside of the distributor 4. The mutual ratio of the amount of air passing through the individual inlets 14.1 14.2 14.3 determines the position of the damper 5, through their adjusting holes 15, Through the shaft 8, through which the arrows 7 are connected, these arrows 7 turn in the same way and all three valves open in the same way 13. In the position of the damper 5 shown in Figure 1, the first inlet 14.1 of the lower primary air and the inlet 14.3 of the secondary air (left and central chamber of the distributor 4) are equally open, while as the second inlet 14.2 of the upper primary air (right chamber) is open only minimally, through the central gap 18 of the damper 5. As a result, the secondary and lower primary air flows into the boiler to the same extent, while only a minimum of the upper primary air moves ... In this position, the damper 5 is located, for example, in a fired boiler when burning conventional fuel, which burns as standard (for example, dry logs). The ratio of the passage of individual types of air in a given position of the damper 5 is shown in Figure 4, i.e. about 45% bottom primary air, about 45% secondary air and about 10% top primary air.

Another possible position of the damper 5, shown in Figure 5, determines the passages of individual types of air so that the maximum passage of about 85% of the secondary air reaches in the inlet 14.3, while for the lower and upper primary air in the inlets 14.1 and 14.2 only the minimum passage determined by the area of the central gap 18 of the damper 5, ie, about 5 - 10%. In this position, the damper 5 is located, for example, for a fired boiler when burning fuel that burns easily (for example, dry wood chips).

Another other possible position of the damper 5, shown in Figure 6, determines the movement of individual types of air so that the maximum passage of about 60% of the upper primary air reaches in the second inlet 14.2. The passage of the lower primary air in the first inlet 14.1 is partially limited and reaches a value of about 30%, and the passage of secondary air in the inlet 14.3 is minimal, since it is determined by the surface of the central gap 18 of the damper 5 and reaches a value of about 10%. The damper 5 is in this position, for example, during firing up or at a fired boiler when burning fuel that is difficult to burn (for example, wet or large logs).

List of related marks

100 heater

1 fuel space

2 fuel

3 upper vent (primary air)

4 distributor

5 damper

6 location

7 boom valve

8 shaft

9 secondary vent (secondary air)

10 bottom vent (primary air)

11 top inlet (primary air)

12 outlet (secondary air)

13 valve

14.1 first inlet (lower primary air)

14.2 second inlet (upper primary air)

14.3 inlet (secondary air)

15 control hole

16 lower outlet (primary air)

17 afterburning space

18 central clearance (flaps)

Claims (3)

1. Solid fuel heater with three-zone air supply for combustion, including a lower outlet (16) of lower primary air, an upper outlet (11) of upper primary air, an outlet (12) and an inlet (14.3) of secondary air, with the secondary air being conducted between the inlet (14.3) and the outlet (12) in a separate vent (9), then includes the first inlet (14.1) of the lower primary air and the second inlet (14.2) of the upper primary air, the lower primary air being conducted between the first inlet (14.1) and the lower outlet (16), is conducted in a separate vent (10), and the upper primary air between the second inlet (14.2) and the lower outlet (11) is conducted in a separate vent (3), characterized in that to each inlet (14.1, 14.2 and 14.3) is connected to a valve (13), each of the valves (13) is mounted on a boom (7), with all three booms (7) closed They are insulated on the shaft (8) and the inlets (14.1, 14.2 and 14.3) are equipped with a common movable flap (5). 2. Heater according to claim 1, characterized in that the inlets (14.1, 14.2 and 14.3) are located on the distributor (4), which is located on the outside of the heater (100), and the shaft (8) is located outside the distributor (4). 3. A heater according to claim 1, characterized in that the movable flap (5) includes two control holes (15).

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