JPS5927991A - Prevention of spontaneous ignition of slack coal - Google Patents

Abstract

PURPOSE:To prevent spontaneous ignition of slack coal under air-borne transport from a feed tank at the bottom of a storage tank, by detecting leak of high- pressure air in the feed tank through valves and introducing an inert gas into the tank whenever the leakage exceeds a predetermined limit. CONSTITUTION:Slack coal is fed from a slack coal tank 2 via valves 4 and 4A into a feed tank 3 for temporary storage. Then valves 4 and 4A are closed and a valve 6 is opened to send slack coal 1 into a transport pipe 7 through a rotary valve 5 so that the coal may be carried by high-pressure air from a compressor 8. The flow rate of the high-pressure air leaking from the valves 4 and 4A and flowing into a storage tank 2 is detected by a flow rate detector 9. When the flow rate exceeds a predetermined limit, the slack coal 1 in the storage tank 2 can generate heat leading to spontaneous ignition and therefore a control valve 12 is opened by a control device 10 and an inert gas is sent into the storage tank 2 through an inert gas supply pipe 11 to prevent the heat generation of the slack coal 1.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method for preventing spontaneous ignition of pulverized coal by feeding inert scum when the amount of high-pressure air leaking from a valve in a supply tank exceeds a certain value.

Conventionally, when transporting pulverized coal over long distances by air or self-transport, it was necessary to transport pulverized coal from a pulverized coal storage tank to a supply tank (after transporting pulverized coal, DI; transport a supply tank). :．The same high pressure as inside the pipe is maintained, and the pulverized coal is pumped through the rotary valve.
1. The material is cut out from the supply tank into the transport pipe and transported using high-pressure air. In this conventional method,
1) When a large amount of pulverized coal is stored in a pulverized coal storage tank for a period of time, the reaction heat due to oxidation of the pulverized coal accumulates, and the pulverized coal gradually accumulates, causing a risk of spontaneous combustion. there were.

Since jXe, there is a method to prevent this spontaneous combustion.

Inert sludge is constantly blown into the pulverized coal storage tank. However, this method has the disadvantage of requiring large amounts of inert gas and being uneconomical.

On the other hand, there is also a method of detecting the temperature in the pulverized coal storage tank and feeding inert scum before this temperature reaches 180 to 250°C, which is the ignition temperature of one pulverized coal.

However, since there is a temperature component i1j in the pulverized coal storage tank, it is extremely difficult to detect the maximum temperature.

Therefore, this method is also not satisfactory.

The purpose of the present invention is to eliminate the drawbacks of the conventional method of upper 6 pins.

To provide a method for surely preventing spontaneous combustion of pulverized coal without using too much inert gas.

The present invention was made by focusing on the fact that the temperature rise of pulverized coal is rate-determining due to co-supply of oxygen in the exothermic reaction between pulverized coal and oxygen. In other words, when transporting pulverized coal by air, the supply tank installed at the bottom of the pulverized coal tank is under high pressure, so air flows through the valve into the pulverized coal storage tank, and the pulverized coal is Partially oxidizes and thus the humidity of the fine A4) charcoal increases over the course of 9 hours due to the accumulation of acid and arsenic.

However, according to the findings of the present inventors, the oxygen consumption rate IW increases at high temperatures, so if the flow rate of the incoming air is, for example, 1 m//r, the oxygen inside the storage tank runs out after about 2 hours and heat generation occurs. I won't. At this point, the pulverized coal is cooled by the four-element gas, which is a component of the air, and the temperature gradient with the outside air becomes large, and the heat radiated from the stored 4VJI wall also becomes fire, so the temperature of the pulverized coal becomes equilibrium and reaches a temperature of about 80℃, for example. It becomes constant at ℃. This temperature is lower than the ignition temperature of pulverized coal (80°C), so it does not reach natural ignition.

In this way, Kitsure Akira et al.
It was discovered that when the leach rate is below a certain value, oxygen supply is insufficient and spontaneous combustion does not occur, and based on this knowledge, the present invention was completed.

The present invention uses pulverized coal 'Fl' 4! : When pulverized coal is cut out from the co-supply tank installed via a valve at the bottom of each tank and air is sent to the low-liquid valve, l (the amount of high-pressure air in the feed tank leaking from the valve is calculated as follows: .

A detector installed between the pulverized coal storage tank and the valve discharges the pulverized coal, and when the amount of leakage remains at a certain value, inert scum is introduced.A method for preventing spontaneous ignition of pulverized coal. be.

The amount of leakage is detected by, for example, detecting the air pressure, flow rate, etc. between the pulverized coal storage tank and a valve located below the pulverized coal storage tank.

In the method of the present invention, an inert gas is introduced into a station building where the amount of leakage exceeds a certain value to block air leaking from the valve and at the same time prevent oxygen from flowing into the pulverized coal storage tank. The pulverized coal is further cooled by inert scum to prevent exothermic reactions.

The following two inventions will be explained in more detail with reference to the drawings.

FIG. 1 is a system diagram of an apparatus showing an embodiment of the method of the present invention. In the figure, pulverized coal 1 is n: pulverized coal storage tank 2
．． Supply tank 3. 4. Valves installed at intervals between the pulverized coal storage tank and the supply tank. Valve 4A, rotary valve/l/7'5, provided at the bottom of the supply tank.

-2 2.7. Bue part (7) /C/L/ 7' 6
+ Becomes a transport pipe.

Pulverized coal 1 is contained in pulverized coal storage tank 2, valve 4 and valve 4.
By opening A, it is supplied into the supply tank δ and temporarily stored. Next, close the valves 4 and 4A, and open the rotary valve FWIS (7) to make the inside of the transport pipe 7 and the supply tank 3 the same pressure, and then pump @pulverized coal into the transport pipe 7 with the rotary valve 5. The material is cut into pieces and transported by high pressure air from the gong resorator 8.

This transport pipe 7 is usually a KI++ long, so the pressure loss caused by 9 μm inside the supply tank was saved! (g/ζIn”G
, resulting in air leaking from the valves 4 and 4A located above them. At this time, since the valves 4 and 4A are worn out due to the pulverized coal being trapped, it is impossible to prevent air from leaking from the one-equipment supply tank 3.

Therefore, in the method of the present invention, the flow velocity of the air leaking from the valve is detected by the flow velocity detector 9, and when the value exceeds the set one shift, ? I7'J elevator 10 Pressure vessel 10 Open the control valve 12 so that it approaches steady state, and open the inert gas introduction pipe 1.
Inert gas such as nitrogen gas is introduced from 1 into the pulverized coal storage 2 to prevent the pulverized coal from generating heat. Close valve 4 at an appropriate time during this time.

The valve 4A's 7-ring property is improved, and from then on, the inert scum is not fed and the operation is switched to normal operation.

As mentioned above, according to the method of the present invention, unlike the Jouto method in which inert scum is constantly blown into the pulverized coal I tank to prevent spontaneous combustion of pulverized coal, air leakage is prevented as described above. Since inert gas is fed only when a certain value is exceeded, there is no need to use a large amount of inert gas, which is economical, and spontaneous combustion can be reliably prevented.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of an apparatus showing an embodiment of the present invention. 2..Pulverized coal storage tank 3..Supply tank 4..Valve 5..Port to tari valve 7..Transport pipe 9..Fluid detection dJ10..Controller
l''...Inert waste introduction pipe 12...Control pulp. Figure 1

Claims (1)

[Claims] When pulverized coal is cut out by a rotary valve from a supply tank installed at the bottom of the pulverized coal storage tank via a valve L2 and transported by air, the leakage amount of high-pressure air in the supply tank from the valve is calculated between the pulverized coal storage tank and the valve. It is characterized by detecting the amount of leakage with a detector installed between the two, and injecting inert scum when the amount of leakage exceeds a certain value. Method for preventing spontaneous combustion of pulverized coal.