Furnace explosion or furnace explosion: the fuel in the steam pot or flue is suddenly burned or flamed out, the gas pressure increases or decreases suddenly, and the talent that can be suffered across the furnace wall or flue causes the disorder of fragmentation.
In the normal environment, the fuel sent to the furnace is incinerated at any time, and the flue gas produced after incineration is always excluded. There is no accumulation of combustible inclusions in the furnace and flue, so there will be no explosion. However, if the operation staff's operation sequence is not proper, the construction or master system plan may differ. It may be that the construction and master system find obstacles, which may generate a large number of combustibles in the furnace environment. When encountering the combustion energy (furnace temperature) suitable for fuel explosion, the accumulated combustibles in the furnace will be incinerated abruptly. The flame spreading rate is very fast, and the smoke produced will be produced The volume of gas increases abruptly, which is not enough to be squeezed out by the furnace, so that the pressure in the furnace increases. When the pressure across the furnace wall is very large, the furnace will explode.
There are two kinds of explosion: external explosion and internal explosion. The former is that the combustible inclusions in the furnace or flue are ignited, resulting in explosive burning which is not controlled rapidly. The volume of gas is rapidly extended, making the furnace wall or flue burst outwards. The latter is furnace fire extinguishing, and the volume of flue gas decreases rapidly with the temperature falling. At this time, if the suction force of induced draft fan is too large due to improper adjustment of forced draft fan and induced draft fan, the furnace wall or flue will suffer great negative pressure and burst inward (this problem is easy to be found in large capacity steam boiler). There is a great risk of explosion, especially external explosion, which will not only cause the furnace or flue to break, the steel frame of the boiler to wind or break, but also damage the relevant heating surface pipes and lead to personal injury and death, repair the problem, stop using for a long time, and even indirect loss.
Accumulation of combustible inclusions in furnace
When the furnace is in normal operation, the fuel sent to the furnace is incinerated at that time, and the flue gas produced after incineration is discharged immediately. There is no accumulation of combustible inclusions in the furnace and flue, so there will be no furnace explosion. A small number of combustible inclusions accumulated in the large volume furnace, even if deflagration, are only "blasting" and will not cause damage.
When the furnace goes out, action shall be taken to cut off all fuel in real time. The faster the cutting, the less fuel entering the furnace, the safer the boiler. If the furnace does not cut off all the fuel in real time after the furnace goes out, the storage volume of the combustibles will increase with the time. At the same time, a small number of one-sided combustibles are pumped to the tail of the boiler to accumulate, a large number of combustibles are gradually raised in the high temperature furnace, and the oxidation feedback connection is accelerated. At this time, if there is oil ignition or turn down the sequence air volume to make the furnace positive pressure or even "shooting", a large number of combustibles such as pulverized coal will be quickly burned in a short time, leading to deflagration. This kind of deflagration has a large energy, which is easy to cause injury or damage to the boiler building. In fact, a certain number of fuels have entered the furnace from the time of excavation and extinction to the time of interval fuel. In addition, the lag time of the coal feeder, the lag time of the valves and baffles and the lax sealing make the amount of fuel entering the furnace reach the deflagration concentration. Miscalibration and misoperation (such as continuous powder feeding and oil feeding) will increase the fuel and combustion supporting atmosphere accumulation. There are several dangerous conditions in the furnace that may generate the accumulation of combustible inclusions as follows:
(1) all furnaces are flamed out without excavation, resulting in the accumulation of combustible inclusions in fuel and atmosphere, which will cause deflagration once they are burned again;
(2) during the normal operation of multiple incinerators, one or several incinerators suddenly fall into the flame and fail to be continuously burned in the furnace, thus accumulating combustible inclusions;
(3) fuel leaks into the disused furnace. Therefore, the furnace purging before and after the boiler combustion is carried out according to the French method, and the ram, oil gun manual valve and gas valve of the coal pulverizer are closed in real time after the boiler is shut down
Furnace extinguishment or incineration deterioration
It has been proved that furnace extinction is the cause of furnace explosion. Furnace extinction refers to the sudden infilling of combustion in the furnace. Unstable combustion of steam boiler is often the precursor of furnace extinction. The following reasons often cause unstable burning of the boiler, and even the furnace goes out:
(1) the auxiliary machine of the steam boiler is obstructed, such as induced draft fan, forced draft fan, coal pulverizer, etc., which suddenly stops running;
(2) improper switching of incinerator and operation of pulverizer;
(3) when the soot blowing of the water wall is insufficient, large area of slag will fall and the flame will be removed;
(4) the water-cooled wall bursts and a large number of steam and water are ejected to blow out the flame, while the furnace temperature is low;
(5) the single end operation of the double in and double out pulverizer makes the separation between the incinerators put into operation too large;
(6) when generating (steam turbine hinders quick load reduction) or (steam boiler hinders quick load reduction), it is improper to take the initiative to dispose (incinerator Management);
(7) the fuel property has changed abruptly, and the stoker has not adjusted in real time, so the new fuel can not comply with the air distribution of raw fuel, especially when the volatile content of fuel is low;
(8) coal cut-off is caused by various reasons (for example, coal pulverizer and coal feeder are blocked in direct blowing system, raw coal pipe, discriminator and primary air pipe are blocked, raw coal bunker is burnt out, coal feeder is blocked in middle storage system, powder bunker is burnt out, lower powder pipe is blocked, primary air pipe is blocked, powder exhauster is blocked in dry agent powder feeding system, etc.);
(9) long time operation under low load or a large number of cool air leaked into the furnace, resulting in a very low temperature level in the furnace, which will be extinguished in case of tension;
(10) the furnace is tense and coking, which destroys the normal energy field in the furnace and makes the air powder in the furnace mixed poorly;
(11) improper operation of soot blowing and decoking, maladjustment of reversing fan and nozzle, and improper operation in case of unstable combustion and insufficient adjustment
——Author：ebico