JPS6327987B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing ignition in an ash storage tank, and more particularly to a method for preventing combustion ash collected by an electrostatic precipitator from igniting in a storage tank.

When dust in exhaust gas emitted from combustion equipment such as heavy crude oil-fired boilers is collected using an electrostatic precipitator, the collected ash is generally transported in a vacuum from the hopper at the bottom of the electrostatic precipitator for processing. The ash collected by the electrostatic precipitator is transported to the first ash storage tank, and then humidified or incinerated. In the case of the latter incineration process, it is necessary to further transport the ash from the first ash storage tank in the previous stage to the second ash storage tank on the incineration equipment side by pneumatic transportation.

FIG. 1 is a diagram showing a transport system for the ash collected by the electrostatic precipitator as described above from the electrostatic precipitator to the second ash storage tank. Dust in the boiler exhaust gas is collected by an electrostatic precipitator 1, and the collected ash 2 is
The ash is carried along with the heated air that has passed through the steam air heater 3, and is further transported by the vacuum pump 4 to the first ash storage tank 5.
transported within. From the first ash storage tank 5 to the second ash storage tank 8
The air 11 in the blower 6 is heated by the steam heater 7 and then transported under pressure. Note that 12 is an incinerator in the latter stage, and 13 is an air line for transferring ash to the incinerator 12.

However, the conventional ash processing operations as described above have the disadvantage that during ash transportation, troubles occur in which a fire ignites and spreads in the storage tank, and the transportation operation has to be stopped to avoid burning out the equipment. .

Originally, the properties of heavy crude oil ash vary slightly depending on the boiler fuel, but its ignition point is a high temperature of 400℃ or higher, and the maximum temperature in the system from the electrostatic precipitator hopper to the second ash storage tank 8 is 150℃. It is unlikely that the ash would spontaneously ignite in this storage tank, since the temperature is around 30°F. As a result of various studies on the cause of the above-mentioned ignition, the inventors of the present invention found that the cause was that the ignition generated in the hopper of the electrostatic precipitator mixed into the ash storage tank as the ash was transported. .

An object of the present invention is to provide an operating method that prevents troubles caused by ignition of ash and spread of fire in the ash storage tank described above.

In order to achieve the above object, the present inventor further investigated and found that the ignition in the ash storage tank is caused by the transportation operation from the lower hopper of the electrostatic precipitator to the first ash storage tank 5.
This is likely to occur when transport operations from the first ash storage tank 5 to the second ash storage tank 8 are performed at the same time, and when the ash level in the first ash storage tank 5 is lower than the ash level in the second ash storage tank 8. was found to be particularly flammable.

The present invention was made based on the above findings, and
The ash transport from the electrostatic precipitator hopper to the first ash storage tank and the ash transport from the first ash storage tank to the second ash storage tank are carried out at different times, and the storage level of ash in the first storage tank is controlled by the rat hole. By making the ash height higher than that in the second ash storage tank to such an extent that it is impossible to prevent the ash from igniting from the electrostatic precipitator hopper, a short circuit to the second ash storage tank is prevented.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings.

FIG. 2A schematically shows a conventional operation pattern of the upstream ash transport device when a problem with ignition of ash occurs in the heavy crude oil ash storage tank. In this operation, the operation of transporting ash from the electrostatic precipitator to the first ash storage tank and the operation of transporting ash from the first ash storage tank to the second ash storage tank are performed in an overlapping manner. Ash ignition or fire spread to the storage tank is unavoidable. On the other hand, in the operation pattern of the present invention shown in FIG. 2B in which the above-mentioned operations are performed at different times without overlapping, it is possible to prevent ignition from entering the ash storage tank and prevent the ash from igniting or spreading the fire. can.

Next, regarding the level of the first ash storage tank, if the ash storage level is low, rat holes will occur as shown in Figure 3A, and if sparks fly from the electrostatic precipitator hopper, they will immediately mix into the second ash storage tank. , 3rd
As shown in Figure B, by managing the ash storage level in the first ash storage tank to prevent ratholes from forming, it is possible to prevent short-circuiting of sparks in the first ash storage tank.

Regarding the second ash storage tank, as shown in Fig. 4, an aeration seat 9 is installed to allow the ash to fall smoothly from the lower cone and chute. Injecting air from the ash storage tank will encourage the spread of fire in the ash, so inert gas such as room air gas is blown into the aeration seat 9 to reduce the oxygen concentration in the ash storage tank and prevent ash from being mixed with ignition material. can prevent the spread of fire.

The present invention can be effectively used not only for heavy crude oil combustion boilers but also for transporting combustible dust and combustion ash from other industrial combustion furnaces.

As described above, according to the present invention, it is possible to prevent ignition of ash and the spread of fire due to mixture of ignition species in the ash storage tank, and smooth ash transport operation and incineration processing are possible.

[Brief explanation of the drawing]

Fig. 1 is an equipment system diagram showing a method of transporting ash collected by an electrostatic precipitator to an ash storage tank, Fig. 2A is a diagram showing a conventional ash transport operation pattern, and Fig. 2B is an operation pattern of the present invention. FIG. 3A is a diagram showing the ash storage level of the conventional first ash storage tank, FIG. 3B is a diagram showing the ash storage level of the present invention, and FIG. 4 is a diagram showing the ash storage level of the conventional first ash storage tank. It is an explanatory view of an ash storage tank. 1... Electrostatic precipitator, 2... Collected ash, 5... First ash storage tank, 8... Second ash storage tank.

Claims (1)

[Claims] 1 In a method of pneumatically transporting the ash collected by a dust collector to a plurality of ash storage tanks connected in series, the ash transport operation from the dust collector to the first ash storage tank and the operation from the first ash storage tank to the second ash storage tank are performed. In addition to carrying out transport operations to the ash storage tanks at different times, the ash level in the first ash storage tank is maintained at a level that does not cause rat holes at all times to prevent short-circuit transport of ash from the dust collector to the second ash storage tank. A method for preventing ignition in an ash storage tank, characterized by retaining the ash.