JP2000320802A - Firing preventer for ash deposited in boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower the temperature of a boiler quickly after extinguishment by disposing a temperature detecting means and a nozzle means for ejecting cooling fluid in a layer of ash deposited at a part in a boiler where the ash is deposited easily thereby preventing the ash deposited on the bottom part in the sub-chamber of the boiler from firing. SOLUTION: Ash ascending from the combustion chamber 1 of a boiler flows, by a small quantity at a time, into the sub-chamber 2 of the boiler through a gap 9 at the water-cooled wall penetrating part of the heat transfer tube 4 of a superheater and ash deposits 3 on the bottom. Since boiler water for adjusting temperature does not circulate through the heat transfer tube 4 and the header 5 of a superheater after the boiler is extinguished, temperature in the sub-chamber immediately after extinguishments of the boiler is about 450-550 deg.C which is substantially equal to the steam temperature. Temperature measuring nozzles 12 and cooling spray nozzles 10 are provided side by side in the sub-chamber 2 of the boiler and when the internal temperature of ash deposited 3 on the bottom exceeds 200 deg.C, inactive gas, e.g. nitrogen gas, or extinguishing water is sprayed from the cooling spray nozzles 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention prevents the burning of sedimentary ash including unburned components generated during the inspection work inside a boiler by burning, and makes the inspection work safe and at a comfortable temperature for a short time. The present invention relates to a device for preventing sedimentary ash from being fired in a boiler, which can be performed in a short time.

[0002]

2. Description of the Related Art In a conventional boiler using petroleum coke as fuel, ash containing particularly unburned carbon is deposited during this combustion. Even after the boiler fire extinguishes, if the ventilation by a blower to promote cooling or natural ventilation by opening the inspection port of the boiler is performed, the deposited ash will ignite due to residual heat in the combustion chamber And burned. In other words, in recent years, the outer wall of the boiler is designed to be kept warm and to minimize the heat dissipation to the outside (ambient) in order to minimize energy loss during normal operation in order to save energy. Therefore, after extinguishing the boiler,
It requires a natural cooling time of about 48 hours. on the other hand,
The time to stop the boiler for inspection inside the boiler, etc.
The company is aiming to minimize it because it has a large effect on production equipment. Here, instead of lowering the temperature of the boiler by natural cooling, it is necessary to forcibly lower the temperature by ventilating the inside. As a forced ventilation means, a forced cooling type using a blower which is an auxiliary equipment of the boiler, a natural cooling type using natural convection by opening an inspection port of the boiler, or a forced cooling type and a natural cooling type described above. However, in both cases, the ash containing unburned carbon deposited in parts other than the combustion chamber of the boiler is ignited by residual heat by actively supplying air (oxygen) to the inside. Burn. This ignition combustion may have an adverse effect on the heat insulation material provided inside,
In any case, the temperature inside the boiler does not decrease, but rather increases.

[0003]

In a boiler using petroleum coke as a fuel, a structure in which a heat transfer tube such as a superheater is allowed to escape to a header side on the basis of a divided water cooling wall is used. The penetrations cannot be completely sealed. For this reason, it is inevitable that a small amount of ash containing unburned carbon (unburned) flows into the sub-chamber of the boiler. This inflow ash is generally deposited on the upper part of the heat transfer tube and the header in the sub-chamber of the boiler, but at the design stage, it is considered that the inflow ash is kept at about 50 mm. on the other hand,
At the bottom of the sub-chamber of the boiler, there is a final reservoir for the ash that falls from the heat transfer tubes and headers, and fly ash also drops heavy and accumulates at the bottom of the sub-chamber. This sedimentary ash does not ignite up to about 200 mm, but in parts exceeding about 300 mm,
The residual heat of the ash is inherent and ignites, leading to combustion. That is, as shown in the cross-sectional structural view of the entire boiler having the sub-chamber including the header of the superheater illustrated in FIG. 1, ignition of the deposited ash occurs most frequently at the bottom of the sub-chamber of the boiler. That is, when the inspection port 6 provided in the sub-chamber 2 of the boiler is opened for ventilation, it is easy for the bottom ash 3 to ignite. The fire extinguishing operation of the bottom ash 6 is performed in a high-temperature working atmosphere, and while paying attention to burns caused by high-temperature objects such as the heat transfer tube 4 of the superheater and the header 5 of the superheater, the worker enters the ignition site, Sprinkle water with a water sprinkler (funnel) to extinguish the fire. When the internal temperature of the sub-chamber is high, the inspection port 6 is closed to stop the oxygen supply and extinguish the fire in order to prevent human beings from entering. Naturally, in this case, because of natural fire extinguishing and natural heat dissipation, the fire extinguishing time cannot be adjusted, and thus the boiler furnace shutdown time is extended. In addition, there is a problem in that the interior of the fuel, which is directly hit by the combustion flame, and particularly the fibrous heat insulating material is deteriorated.

[0004] It is an object of the present invention to prevent a phenomenon in which sedimentary ash of a boiler, in particular, sedimentary ash at the bottom of a sub-chamber of a boiler ignites and burns, and after extinguishing the boiler, the temperature is quickly lowered by ventilation.
It is an object of the present invention to provide a boiler ash prevention device that can perform internal inspection work or repair work safely and at a comfortable temperature.

[0005]

Means for Solving the Problems In order to achieve the above object, the present invention is configured as described in the claims. That is, as described in claim 1, when stopping the boiler and performing an internal inspection, the apparatus prevents ignition of accumulated ash including unburned components due to the supplied air and residual heat of the boiler combustion chamber. A device for preventing ignition of sedimentary ash, wherein at least a temperature detecting means and a nozzle means for ejecting a cooling fluid are arranged in a layer of the sedimentary ash in the portion where the ash easily accumulates inside the boiler. is there. Claim 2
As described in claim 1, in claim 1, the deposition site of the deposited ash is a bottom portion of a sub-chamber of a boiler in which a heat transfer tube of a boiler penetrates a water cooling wall and a header portion of each heat transfer tube is disposed. A device for preventing ignition of sedimentary ash, wherein at least a temperature measurement nozzle and a nozzle for jetting a cooling fluid are provided at a position at a height of 100 to 200 mm, more preferably at a position of 150 to 200 mm from the bottom of the sub-chamber. It is assumed that. Further, as set forth in claim 3, in claim 1 or claim 2, the nozzle means for jetting the cooling fluid comprises:
This is an apparatus for preventing fire of deposited ash as nozzle means for ejecting an inert gas, for example, a gas having low reactivity such as nitrogen gas or carbon dioxide gas. In addition, as described in claim 4, in claim 1 or claim 2, the nozzle means for jetting the cooling fluid is a nozzle means for jetting cooling water or fire extinguishing water, and is an apparatus for preventing fire of deposited ash. Things. Further, as set forth in claim 5, in claim 1 or claim 2, the nozzle means for jetting the cooling fluid comprises at least one of an inert gas, cooling water, and fire extinguishing water.
This is an apparatus for preventing fire of deposited ash as nozzle means for ejecting seeds.

The device for preventing ignition of sedimentary ash in the boiler of the present invention can easily remove nitrogen from the outside of the ash accumulation portion containing unburned components, that is, usually from the "inspection platform" for the maintenance and inspection walkway. Supply inert gas with low reactivity such as gas, or cooling water or fire extinguishing water to blow off and disperse the deposited ash containing unburned components, and at the same time reduce the heat dissipation and ambient temperature of the deposited ash. It is possible to easily prevent ignition and burning of the deposited ash. In addition, the surrounding temperature can be quickly lowered by ventilation after the fire of the boiler is extinguished, and the internal inspection and repair work can be efficiently performed under a safe and comfortable environment temperature.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic diagram showing an example of the overall sectional structure of a boiler having a sub-chamber including a header of a heat transfer tube such as a superheater to which the present invention is applied. FIG. 3 is a schematic view showing an example of a case where a nozzle for spraying the inert gas or fire extinguishing water of the present invention is attached to a sub-chamber of a boiler. In FIG. 1, the ash that has risen from the combustion chamber 1 of the boiler passes through the water-cooling wall penetration portion gap 9 of the heat transfer tube 4 of the superheater.
It flows into the sub-chamber 2 of the boiler little by little, and this is deposited to form bottom sedimentary ash 3. After extinguishing the boiler and stopping it inside the heat transfer tube 4 of the superheater and the header 5 of the superheater,
Since the boiler water for temperature control is not circulated, the temperature of the sub-chamber immediately after the fire of the boiler furnace is about 450 to 550 ° C., which is the same as the temperature of the steam. As shown in FIG. 2, a temperature measurement nozzle 12 and a cooling spray nozzle 10 are provided in parallel in the sub-chamber 2 of the boiler, and the internal temperature of
When the temperature becomes 0 ° C. or higher, the cooling spray nozzle 10 is adjusted to spray an inert gas such as nitrogen gas, carbon dioxide gas or the like, which has low reactivity, or fire-extinguishing water. In this case, the coupler 11 was provided so that the inert gas or the fire extinguishing water could be connected (connected) with one touch. In addition, sub-room 2 of boiler
In the part where the height of the bottom sedimentary ash 3 exceeds about 300 mm, since the internal heat is stored in the central part of the sedimentary ash, the height from the bottom of the sub-chamber 2 of the boiler is 100 to 200 mm, more preferably 150 to A temperature measuring nozzle 12 and a cooling spray nozzle 10 were provided at a height of 200 mm. In the apparatus for preventing ignition of sedimentary ash in the boiler of the present invention, the temperature measuring nozzle 12
The cooling spray nozzle 10 is provided. First, the temperature inside the sedimentary ash is measured by the temperature measuring nozzle 12, and when the temperature inside the sedimentary ash becomes about 200 ° C. or more, nitrogen gas, carbon dioxide Spraying inert gas such as gas or spraying cooling water and fire extinguishing water to prevent ignition and burning of sedimentary ash including unburned components, and after fire extinguishing, immediately lower the ambient temperature by ventilation, The maintenance and inspection or repair work of the inside can be performed under a comfortable temperature.

[0008]

According to the apparatus for preventing ignition of deposited ash in a boiler of the present invention, a nozzle for temperature measurement and a cooling spray nozzle are provided at a portion of the deposited ash containing unburned components. When the temperature rises to about 200 ° C or more, the cooling spray nozzle blows out inert gas such as nitrogen gas or carbon dioxide gas, or sprays cooling water or fire extinguishing water to unburn. Prevents the ignition and combustion of sedimentary ash containing air, and after the fire is extinguished, quickly lowers the ambient temperature by ventilation to efficiently perform internal maintenance and inspection or repair work at a safe and comfortable temperature. There is an effect that can be performed well.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of a cross-sectional structure of an entire boiler having a sub-chamber including a header such as a superheater illustrated in an embodiment of the present invention.

FIG. 2 is a schematic view showing an example in which a nozzle for ejecting inert gas or spraying fire-extinguishing water, which is exemplified in the embodiment of the present invention, is attached to a sub-chamber of a boiler.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Boiler combustion chamber 2 ... Boiler sub-chamber 3 ... Bottom sedimentary ash 4 ... Superheater heat transfer tube 5 ... Superheater header 6 ... Inspection port 7 ... Burner 8 ... Exhaust flue 9 ... Water cooling wall penetration gap DESCRIPTION OF SYMBOLS 10 ... Cooling spray nozzle 11 ... Coupler 12 ... Temperature measuring nozzle 13 ... Deposited ash 14 ... Water cooling wall 15 ... Heat transfer tube 16 ... Header 17 ... Air-water drum 18 ... Flow meter 19 ... Temperature meter

Claims (5)

[Claims] 1. An apparatus for preventing the accumulation of unburned ash due to the supplied air and residual heat of a boiler combustion chamber when the boiler is shut down for internal inspection. An apparatus for preventing fire of deposited ash in a boiler, wherein at least a temperature detecting means and a nozzle means for ejecting a cooling fluid are provided in a layer of the deposited ash at a portion where the ash is likely to be deposited. 2. The method according to claim 1, wherein the deposition site of the deposited ash is:
The heat transfer tube in the boiler penetrates the water cooling wall, and the bottom of the sub-chamber of the boiler in which the header portion of each heat transfer tube is provided,
In a position having a height of 100 to 200 mm from the bottom of the sub chamber,
An apparatus for preventing ignition of deposited ash in a boiler, comprising at least a temperature measurement nozzle and a nozzle for jetting a cooling fluid. 3. An apparatus according to claim 1, wherein said nozzle means for jetting a cooling fluid is a nozzle means for jetting an inert gas. 4. An apparatus according to claim 1, wherein said nozzle means for jetting a cooling fluid is a nozzle means for jetting cooling water. 5. A boiler according to claim 1, wherein the nozzle means for jetting the cooling fluid is a nozzle means for jetting at least one of an inert gas and cooling water. Fire prevention device for sedimentary ash.