JPS6036522B2 - boiler equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a boiler device, and particularly to a boiler device that burns coal, oil, gas, etc. to generate steam, and which reduces the amount of nitrogen oxides contained in the combustion exhaust gas. This invention relates to a boiler device having an improved and novel structure for the purpose of the present invention.

In boiler equipment that generates steam by burning Japanese fuels such as coal, oil, and combustion gas, nitrogen oxides ( There is a strong social desire to reduce the amount of N○k (hereinafter referred to as N○×) to zero or to the lowest possible amount.

The following methods are currently being implemented or being considered for application for the above purpose. That is, 'i} two-stage combustion method, 'o} gas recirculation method,
1 = A combination of the one-stage combustion method and the gas recirculation method, but both reduce the temperature of the flame in the boiler and reduce the oxygen concentration around the combustion flame to reduce N○×
This is done in consideration of reducing the Another possibility is to increase the heat transfer surface of the boiler and reduce its heat load, but in this case, the combustion efficiency in the volumetric burner section of the furnace will decrease and the incomplete combustion area will increase. , the amount of unburned carbon increases, leading to an increase in the amount of dust in the exhaust gas. In particular, the recent movement to regulate N○k has been extremely strict, and there is a trend that it will be mandatory to suppress the amount to around 150 ppm. However, this is a value that is extremely difficult to achieve even with the current state of technology, and it must be said that the possibility of simply improving the combustion method is slim.
Furthermore, as mentioned above, there is a major problem in that the amount of dust in the exhaust gas increases. FIGS. 1 and 2 are explanatory diagrams showing the configuration of a boiler apparatus having a conventional configuration including the above-mentioned problems. Combustion air is introduced from an air blower 1 into an air duct 2, The air duct 2
A part of the combustion exhaust gas sent from the gas recirculation fan 3 is mixed by the mixing device 4, and is further sent into the load burner wind box 5 and the = J stage combustion wind box 6, but at this time, the partition plate 10 and distribution damper 11. Fine adjustments in air distribution are made using the load burner air register 7 and the two-stage combustion air register 8.
× As a measure to reduce gas, use the above load burner resistor 7.
The shortage of air amount from the above two-stage combustion register 8
Methods have been devised and implemented to reduce the production of NOk gas by replenishing NOk gas by replenishing NOk gas, delaying the combustion reaction in the furnace 9, and lowering the flame temperature. However, in the configuration described above, since the height from the bottom burner to the first stage combustion air register 8 is high, the fuel discharged from the burner, so-called unburned fuel, is in a state where there is insufficient air. Since it is exposed to high temperatures, it is thought to be carbonized by thermal decomposition, polymerization, etc. In addition, the air from the air register 8 for two-stage combustion has a residence time longer than necessary because the furnace cross section hardly changes, and it is not easily mixed with the gas in the furnace and is easily carbonized. The burning rate of the fuel is slower than that of non-carbonized fuel, resulting in a problem of longer combustion time. Therefore, the fuel is sufficiently combusted in the furnace 9 and is surprisingly discharged to a low temperature range, resulting in an increase in the amount of dust in the exhaust gas. This is also NO
This means that it is difficult to sufficiently apply measures to reduce K gas, and as a result, it becomes impossible to effectively suppress N○x gas. The present invention has been made in view of the problems seen in the prior art as explained in detail above. On the other hand, there is a double direction in which the unburned content of the fuel increases rapidly, and the conditions for introducing air from the first-stage arm combustion air port (NO boat, hereinafter referred to as NO boat) are such that the unburned content of the fuel increases rapidly. It is believed that if combustible materials are exposed to high temperatures for a long time under conditions that are less than the theoretically calculated amount of combustion air, the fuel will be carbonized, and this carbonized combustible material will The time required to burn is 3 to 4 times longer than that of non-carbonized
As a result of the theoretical study, it was confirmed that due to the increase in the length of the boiler, the combustion was not completed effectively, resulting in an increase in the amount of dust. , arch-shaped protrusions facing each other are provided in the furnace, the venturi throat formed by these protrusions divides the furnace into a primary combustion chamber and a secondary combustion chamber, and NO is placed near the venturi throat. The main point is to provide an air supply V inlet for secondary combustion as a boat, and as a desirable embodiment, an auxiliary burner (afterburner) is further provided near the venturi to stabilize the flame in the secondary combustion chamber. Efficient NO by recirculating exhaust gas to the load burner and/or secondary combustion air supply port
It measures the reduction of skin.

The boiler apparatus of the present invention will be described in further detail below with reference to the accompanying drawings.

FIG. 3 is an explanatory diagram showing the configuration of one embodiment of the boiler apparatus of the present invention. As already explained, the furnace is connected to the primary combustion chamber 3.
The furnace is separated into a combustion chamber 1 and a secondary combustion chamber 32, and the cross section of the furnace that connects the primary combustion chamber 31 and the secondary combustion chamber 32 has a venturi-like structure formed by an arch-shaped protrusion. It constitutes the throat section 33.

As a result, the furnace gas becomes a contracted flow, the flow velocity is increased, and the residence time is shortened. Further, the venturi throat 33 is provided with a two-stage combustion air port (air register NO port) 38, and the furnace gas and combustion air are rapidly and uniformly mixed by the venturi effect. In this case, since a suction action occurs at the venturi throat, the pushing pressure of the slave is sufficient for the second stage (secondary) combustion air. Further, since the protrusion is arch-shaped in the corner of the upper space of the primary combustion chamber 31, the venturi throat passes smoothly without generating a vortex, so that the progress of the force-bonization of unburned components can be suppressed. Further, since the protruding portion is formed in an arch shape, the pressure loss of the fluid is reduced, which is advantageous in the case of a boiler having heat exchanger tubes. Further, an auxiliary burner (afterburner) 34 is arranged in the same horizontal plane as the J saddle combustion air port 38, either parallel to each other or facing the primary combustion chamber 31 side. This makes it possible to stabilize combustion in the secondary air chamber. Combustion air passes through an air duct from an air blower (not shown) and is mixed with a portion of the combustion exhaust gas sent from a gas recirculation fan, and is then mixed with a portion of the combustion exhaust gas sent from the gas recirculation fan, and is then transferred to the air register 37 for the load burner and the above-mentioned J-stage window burning air. It is fed through the port 38, which is essentially the same as in the boiler device of the prior art structure described in connection with FIGS. 1 and 2, but in the case of the present invention. The mixing conditions of the air from the NO boat 38 and the furnace gas are effectively improved compared to the prior art. Therefore, it is possible to suppress the amount of oxygen consumed in the primary combustion chamber 31 to a low value, and as a result, the N○× concentration is maintained at a low value. Furthermore, as the mixing conditions of the air from the NO boat 38 and the furnace gas are improved, the mixing conditions of the air from the auxiliary burner 34 and the upper NO boat 38 are improved, and eventually the two The fuel in the combustion chamber 32 is completely combusted, thereby reducing the amount of dust in the exhaust gas. As explained in detail above, according to the present invention, despite the extremely simple structure, the amount of N○× gas contained in the exhaust gas can be effectively reduced, and the amount of dust contained in the exhaust gas can be reduced. It has revolutionary effects such as lowering the amount of carbon dioxide, which greatly contributes to preventing environmental pollution and suppressing the occurrence of pollution.

[Brief explanation of the drawing]

FIGS. 1 and 2 are explanatory diagrams showing the configuration of a boiler apparatus according to the prior art, and FIG. 3 is an explanatory diagram showing the configuration of an embodiment of the boiler apparatus of the present invention. 31...Primary combustion chamber, 32...Secondary combustion chamber, 33...Venturi throat, 34...Auxiliary burner, 35...For load burner Wind box, 37...Load burner air resistor, 38...
...Air register for low-stage combustion. Figure 1 Figure 3 Figure 2

Claims (1)

[Claims] 1. Arch-shaped protrusions facing each other in the furnace are provided,
A primary combustion chamber is formed on the upstream side of the furnace gas at the throat of the bench lily formed between the protrusions, and a secondary combustion chamber is formed on the downstream side, and a load burner that burns in a state of insufficient combustion air is provided in the primary combustion chamber. . A boiler device characterized in that a secondary combustion air supply port is provided near the throat of the bench lily to supplement the insufficient combustion air in the load burner. 2. The boiler device according to claim 1, wherein a part of the combustion exhaust gas of the boiler device is supplied to the load burner and/or the secondary combustion air port.