JPS587A - Combustion device - Google Patents

Abstract

PURPOSE:To contrive the enlargement in high-load combustion and TDR (Turn Down Ratio) control range in a burning device, by installing on the combustion chamber walls secondary air injection holes that lead to the secondary air chamber installed outside the combustion chamber so that the secondary air may be directed stepwise to the flame. CONSTITUTION:The amount of secondary air to be supplied via the No.1 passage 3 and the No.2 passage is properly adjusted through the adjustable dampers 6 and 21 as well as through the adjustable damper 7 installed in the secondary bypass 19 to be fed into the secondary air chambers 8 and 9. The secondary air is then blown out of the secondary air outlets 10 and 11 to be directed uniformly at the flame forming in the combustion chamber 15. The secondary air jet stream spreads the flame all over the combustion chamber 15 so that the flame undergoes heat exchange at the heat exchanger 17 provided with united pipes and fins. The flame is then led to the exhaust chamber 20 to be mixed with the air from the secondary air bypass 19 and discharged from the exhaust port 18. In this way, large scale combustion is made possible in a combustion chamber which is small in size.

Description

[Detailed Description of the Invention] The present invention relates to a combustion device for supplying forced air using a fan or the like in hot water supply equipment, heating equipment, etc., and an object of the present invention is to provide a combustion device that satisfies the following items. .

(1) Achieve high-load combustion with a combustion chamber load on the order of 1 dKC2L1/hm5, and aim to downsize the combustion chamber.

(2) To improve usability when applied to equipment,
To maintain good combustion even if the amount of combustion changes over a wide range.

(3) To maintain good combustion even when using various fuels with different characteristics and to make the combustion device universal.

(4) In addition to simplifying the configuration of the combustion device, we aim to downsize the entire combustion system including the fan, improve the reliability of the combustion device, and strengthen its ability to respond to various devices.

In general household combustion equipment, the premixed gas ejected from the burner nozzle forms a primary flame above the flame nozzle, and a secondary flame is formed in the downstream region of the flame that entrains surrounding air and burns. In hydrocarbon fuels, two-flame is an oxidation process of unburned components containing large amounts of CO and H2, and the oxygen supply is performed by so-called entrainment (entrainment of surrounding air) and molecular diffusion, so the reaction rate is slow, and the flame is in the wake. Stretch towards. -Increasing the fire/air ratio causes most of the reaction to occur in the primary flame, so the secondary flame becomes shorter. - In combustion in which the air in the flame is increased to exceed the theoretical air, so-called secondary combustion, secondary flames are almost never seen, but on the other hand, oscillatory combustion is likely to occur, and since the flame is in close contact with the flame nozzle, the flame nozzle is It often heats up and causes flashbacks. Since the combustion range is still relatively narrow, highly accurate control of the amount of premixed air is required. Furthermore, in hot water supply and space heating, it is required to greatly vary the amount of combustion in response to seasonal changes in water temperature and air temperature, as well as changes in load (during multiple hot water supply and multiple room heating). In other words, the ratio between the maximum combustion amount and the minimum combustion amount that can maintain good combustion conditions, so-called T D
It is required to increase R (Turn Down Ratio). Therefore, if T111R is set to a large value, highly accurate flow rate control is required at a minute flow rate, which has the disadvantage of making the device complicated and large.

On the other hand, Bunsen combustion, in which the amount of air in the flame is set below the theoretical amount of air, has a wider combustion range. Therefore, it is possible to increase TI)R without using highly accurate control of the primary and secondary air amounts and the total combustion. However, because the two flames elongate significantly, high-load combustion cannot be achieved with this method. Therefore, many attempts have been made to achieve high-load combustion by forcibly feeding air using a fan or the like to accelerate the combustion reaction and shorten the flame.

As one conventional example, a burner 101 as shown in FIG.
Nearby there is a combustion device having a configuration in which secondary air supplied by a fan 102 is deflected by a guide plate 103 and introduced into the flame. In this case, when the amount of supplied air is increased, air is also supplied to the base of the burner 100 at a high speed, making the flame itself unstable. Conversely, if the supply amount is reduced, the guide plate 103 restricts the flow and most of the gas flows parallel to the combustion gas, reducing the amount of gas supplied into the flame and preventing the flame from becoming shorter. Furthermore, since the guide plate 103 becomes hot, its material and durability become problematic, and there is a limit to how high the load can be applied, as it becomes difficult to extend the guide plate 103 close to the flame.

There is another conventional example shown in FIG. 8 that has a similar configuration. This is because secondary air that has passed near the burner 104 is deflected by a baffle 105 and supplied to the flame. In this case, the structure becomes more complicated than the case shown in FIG. 7, and the fuel capacity of the combustion chamber including the baffle 105 becomes larger. Therefore, it is easy to cool the flame and cause incomplete combustion,
The combustion range becomes narrower. For this reason, there are restrictions on the machining dimensional conditions of each part and the control of the amount of air supplied, making it impossible to obtain a large TDR.

In another embodiment shown in FIG. 9, a water-cooled combustion chamber wall 10 is used.
6, and air is supplied toward the flame from a secondary air outlet 107 in the center of the combustion chamber. This system has a relatively simple structure and can achieve high-load combustion because secondary air is directly injected and supplied to the secondary flames. However, since the flame is constantly cooled by the combustion chamber wall 107, when the combustion amount is reduced, the combustion chamber wall 107
7 increases, flame cooling occurs, the combustion reaction is frozen, and unburned substances such as GO are discharged as they are. Therefore, TDR cannot be set large.

Furthermore, there is a combustion device shown in FIG. 10 as another conventional example.

A flame port plate 109 is inserted into an inner cylinder 108 that forms a combustion chamber, and an outer cylinder 11Q is provided around the outer periphery of the inner cylinder 108 to form a secondary air chamber 111. The secondary air supplied here is ejected from the secondary air outlet 112 provided in the inner cylinder 108 toward the flame formed on the flame port plate 109, and by forced mixing, the flame is shortened and the flame is increased. The load is what the Burning Kim Song is trying to manifest. In this case, flame is formed not only in the center of the combustion chamber but also in the vicinity of the inner cylinder 1o8. Therefore, the inner cylinder 108 becomes high in temperature, causing problems in heat resistance and durability, and at the same time, the air in the secondary air chamber 111 is heated and expands, and the internal pressure of the secondary air chamber 111 increases. Therefore, in order to send the required amount of air into the combustion chamber through the secondary air outlet 112, a fan with high blowing pressure is required, which has the disadvantage of increasing the size of the fan and raising the noise level. The ability to respond is not sufficient.

As explained above, none of the conventional combustion devices intended for high-load combustion can simultaneously satisfy high-load combustion and expansion of TDFI. Furthermore, the combustion device has become complicated, and miniaturization of the entire combustor including the fan has not been sufficiently pursued.

The present invention consists of a combustion chamber wall made up of fins and water pipes to serve as a heat exchanger, and a part of the combustion chamber is provided with multiple secondary air jet ports to stabilize the secondary air temperature (normal temperature level) and air jet speed according to the load. By supplying air with different values, the above-mentioned conventional drawbacks can be overcome. An embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

1 and 2, 1 is a fan that supplies combustion air, and its supply port 1' is connected to the primary air passage 2 and the first passage 3. of the secondary air supply passage. A secondary bypass passage 19 is provided which communicates with the second passage 4 and extends from a part of the secondary air supply passage. Movable dampers 6°6, 7. for air adjustment are installed in each passage 2°3, -4.19. 21 is placed in the middle.

The first passage 3 communicates with a secondary air chamber 8 which also serves as a pressure equalization chamber provided downstream thereof, and the second passage 4 also leads to a secondary air chamber 9. The secondary air chambers 8 and 9 are in close contact with the fin and pipe integrated heat exchanger section 16 forming the combustion chamber 16, and are in communication with secondary air jet ports 10 and 11 provided in a part thereof. The secondary binorth passage 19 communicates with an exhaust chamber 20 provided downstream of the combustion chamber 15.

Reference numeral 13 denotes a burner main body, and the burner port 14 faces the combustion chamber 15, and is located in stages with the secondary air jet ports 10 and 11 in the combustion chamber 16 downstream of the burner port 14. Burner body 1
A primary air passage 2 communicates with the upstream side of the primary air passage 4, and a fuel injection nozzle 12 is installed in the passage. 1 is a water passage of the fin-pipe integrated heat exchanger 16, and 18 is an exhaust outlet provided downstream of the combustion chamber 16.

The second operation of the combustion apparatus of the present invention having the above-mentioned configuration will be described. A part of the combustion air supplied by the fan 1 passes through the primary air passage 2, is adjusted to an appropriate supply amount by the movable damper 6, and is then mixed with fuel injected from the fuel injection nozzle 12 provided midway. The mixture becomes a mixture and is sent to the burner body 13. The air-fuel mixture supplied to the burner body 13 is further mixed and rectified, and then uniformly jetted into the combustion chamber 15 from the flame port 14 to form a flame.

On the other hand, the secondary air supplied through the first passage 3 and the second passage is connected to the movable air pass passage 1.
After adjusting the supply amount to an appropriate amount according to the combustion amount with the movable Danno ζ-7 in 9, it enters the secondary air chamber 8゜9, passes through the secondary air jet nozzle 10.11, and is evenly distributed into the combustion chamber 16. It turns toward the flames that form within. The flame spreads over the entire combustion chamber 15 due to this secondary air jet, and after exchanging heat with the fin-like integrated heat exchanger 17, air from the secondary air bypass passage 19 flows into the exhaust chamber 20. and is discharged from the exhaust outlet 18. The heat medium in the water passage is usually
Water is used, but depending on the purpose, there is no problem if the heat medium can be transported such as oil or Freon gas.

Next, the operation of the above combustion device will be explained using FIGS. 3 to 6. When the amount of combustion is large, the first passage 3. The movable damper 6.21 provided in the middle of the second passage 4 is opened and the movable damper 7 for air purification is closed to set the amount of air. The secondary air is injected towards the flame formed within the combustion chamber 16. In this case, the condition is that the secondary air flow velocity on the upstream side is set higher than that on the downstream side.

As mentioned above, the secondary flame contains a large amount of unburned components such as CO and H2, but the forced air supply and forced mixing by secondary air injection to this flame significantly accelerates the oxidation reaction. In particular, by setting the air flow velocity high on the upstream side, this tendency will further increase. In this way, as shown in Fig. 3, the secondary flame is spread over almost the entire area of the combustion chamber 15 due to the secondary air jet, and the space of the combustion chamber 15 is fully utilized to allow the combustion reaction to take place in that area. It is done. Therefore, even if the combustion chamber 15 is small, a large amount of combustion is possible, and the load on the combustion chamber can be about 1 to 2 KcalX10', i-. In addition, the flame spread over almost the entire area inside the combustion chamber 16 undergoes sufficient heat exchange with the fin-pipe integrated heat exchanger 17, which greatly reduces the temperature rise of the secondary air inside the secondary air chambers 8 and 9. At the same time, the temperature rise at the secondary air outlet 10.11 is also small, and a stable secondary air supply is maintained. Therefore, it is possible even if the blowing pressure of the secondary air supply reservoir is small.
It is also smaller and produces less noise.

On the other hand, if the flame is narrowed down in this state, the secondary flame B will be strongly influenced by the secondary air supplied from the secondary air outlet 10 and will approach the flame outlet 14, as shown in FIG. An explanation will now be given based on FIG. 6, which shows the relationship between combustion chamber load and CO concentration. In the case of fuel with a low combustion rate or a fuel with a low diffusion rate, the balance with the heat generation rate due to the combustion reaction is lost due to rapid cooling due to the secondary air injection from the secondary air jet port 1o to the flame base, resulting in a decrease in the combustion reaction. Causes freezing and lifting. Therefore, as shown in curve a, when the combustion chamber load becomes low, unburned components such as CO are suddenly generated. In addition, when using fuel with a high burning speed, the flame adheres closely to the flame nozzle 14, and the movable damper 6 provided in the first passage 3 is closed to the flame nozzle in the shaded area V of the curved line. By opening the movable damper 7 provided in supply secondary air. The secondary air outlet 11 expands and expands due to lack of oxygen. In this case, since there is no rapid cooling of the flame base as in the case of FIG. 4, - the flame becomes a stable flame without being disturbed by air flow. Therefore, the area upstream of the secondary air nozzle 11 becomes a stable high temperature region, so rapid flame cooling by the secondary air can be avoided, and even when fuel with a low combustion rate or a fuel with a low diffusion rate is used, the combustion chamber 15 The flame C that spreads inside continues stable combustion. Furthermore, even in the case of fuel with a high burning speed, two flames C
Since the flame spreads widely in the combustion chamber 16, it separates from the flame nozzle 14 and its effectiveness in heating it is significantly reduced. Therefore, as mentioned above,
The red heat of the flame outlet 14.

Flashback phenomenon can be completely prevented. By satisfying these conditions, it is possible to obtain the characteristics of curve C shown in Figure 6 for any fuel, and achieve good combustion in a wide range of combustion chamber loads, that is, in a large TDR region. be able to.

In addition, by bypassing the secondary air, the fan will not be used in an overloaded state, greatly improving the reliability of the combustion device.
This method is effective in preventing condensation of exhaust gas. Moreover, even when the combustion amount changes, since only the air control on the combustion side is performed, the exhaust gas discharge pressure from the exhaust outlet 18 is sufficient, and it is possible to sufficiently cope with the conversion to FF and FK.

As is clear from the above description, the combustion apparatus of the present invention provides the following effects.

(1) By injecting secondary air into the flame and changing the air flow velocity on the upstream and downstream sides, forced air supply and forced mixing are effectively promoted, and the combustion reaction is achieved throughout almost the entire combustion chamber space. By promoting this process, large-capacity combustion can be achieved in a small combustion chamber, thereby realizing downsizing of the combustion device.

(2) A plurality of independent secondary air chambers are provided in the flow direction of combustion gas, and secondary air is supplied to the flame from all air outlets during large combustion, and from the downstream side during small combustion. By reducing the air supply and slowing the air flow velocity, high-load combustion and stable combustion at low loads are made possible, and the performance of TDR combustion is achieved.

(3) In addition to controlling the secondary air supply method described above, since there is no need to provide a guide plate or baffle inside the combustion chamber, the combustion chamber has a simple configuration and is suitable for various fuels with different characteristics. Both can maintain good combustion and make combustion devices universal.

(4) By configuring the combustion chamber wall as a heat exchange part and providing a jet nozzle, it is possible to prevent the temperature rise in the secondary air chamber, reduce air heating, and lower the internal pressure, resulting in low blowing pressure. Since a small fan can be used, noise is reduced and the entire combustor system can be made smaller and lighter. Furthermore, the cost advantage is also sufficient.

(5) Since it is a secondary air bypass system, TDR combustion can be easily achieved without the need to control the air volume of the fan, and exhaust gas condensation due to bypass air is prevented, and the exhaust discharge pressure does not change, so the combustion system FF conversion, FE
sufficient wind resistance performance can be ensured even in the case of

[Brief explanation of drawings]

Fig. 1 is an overall sectional view showing an embodiment of the combustion apparatus of the present invention, Fig. 2 is a perspective view showing a cross section of the combustion apparatus, and Figs.
Fig. 5 is a cross-sectional view showing the flame state formed by the same combustion device, Fig. 6 is a characteristic diagram showing the CO concentration with respect to the combustion chamber load during TDR combustion in the same combustion device, and Figs.
The figure is a sectional view of a conventional example. 1...Fan, 3...1st aisle, 4.
...Second passage, 6. 7. 21...Movable damper, 8,9...Secondary air chamber, 1o, 1
1... Secondary air outlet, 13... Burner body, 14... Flame port, 16... Combustion chamber, 16... Fin-pipe integrated heat exchanger,
19... Secondary air bypass passage, 20...
...Exhaust room, people. B. 0...Two flames. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 *v! ! , ¥'f4'; @ tro' (*rd/H
, p) Figure 7 Figure 8 Figure 9 DG

Claims (1)

[Claims] A combustion apparatus comprising a combustion chamber, a device for supplying combustion air, and a means for introducing secondary air onto a burner with a flame port facing into the combustion chamber, wherein the combustion chamber has a heat exchanger configuration. In addition, a plurality of secondary air nozzles are provided in the combustion chamber wall, and a plurality of secondary air chambers communicating with the secondary air nozzles are arranged outside the combustion chamber wall in stages independently of each other in the flow direction of combustion gas. A stepwise air supply method is established for the flame, and the air flow rate from the secondary air outlet is controlled by guiding the secondary air bypass circuit to the exhaust chamber and set in response to changes in the amount of combustion. A combustion device featuring: