Analysis of blast furnace blast

　　agglomeration process

　　■ if the personnel fail to comply with the safety operation regulations, gas maintenance safety regulations, and do not wear labor protection articles, gas poisoning, gas explosion, scalding, electric shock, mechanical injury and other accidents may be caused.

　　■ gas pipelines, valves and dehydrators shall be inspected and maintained every shift. In case of valve failure or leakage. It may cause gas poisoning and gas explosion accidents.

　　■ before starting the equipment, it must be confirmed that there is no one or other sundries in the sintering machine. Otherwise, gas poisoning, gas explosion, scalding, electric shock, mechanical injury and other accidents may be caused.

　　■ during the ignition process of the burner, explosion, fire, poisoning and suffocation may be caused due to no quick shut-off valve, low gas pressure, leaking gas, mixed air in the gas pipeline, failure to confirm each valve before ignition, no gas leakage monitoring system on site or system failure.

　　■ during the production process, due to water and power cuts, the supply of gas water seal can not be guaranteed, or the water seal is waterless due to the failure of the gas water seal system, gas pipeline leakage, excessive gas pressure and other reasons, and the low height of the gas vent will lead to gas accumulation on the site. In case of high temperature and open fire, explosion and fire will also occur, and poisoning and suffocation will also occur.

　　■ when igniting, the kindling shall be delivered first, and then the gas shall be turned on. Otherwise, gas explosion may occur.

　　Blast furnace ironmaking process

　　Furnace top equipment system

　　■ after the wind shutdown maintenance, there is a danger of poisoning, suffocation and gas explosion when the air is supplied without the consent of the person in charge of wind shutdown.

　　■ when the wind needs to be stopped, the water supply is not stopped first, and the furnace top gas is ignited. Gas leakage may occur, resulting in gas poisoning, suffocation, combustion and explosion.

　　■ when the pressure on the top of the furnace increases continuously and cannot be controlled, there is a risk of explosion if the air is not reduced in time and the top vent valve is not opened.

　　■ before shutdown, the blast furnace and gas system are not reliably separated; When the boiler is shut down by water pumping method, the conical cap on the top blow off valve or the blow off pipe is not removed; The counterweight of the blow off valve on the top of the furnace is not lightened when the method of water pumping with empty material of recovered gas is adopted; Gas leakage has occurred, resulting in gas poisoning, suffocation, combustion and explosion.

　　■ the cold air duct does not maintain positive pressure; The dust collector, furnace top and gas pipeline are not filled with steam or nitrogen or the residual air is not completely removed; After air supply, the gas pressure at the top of the blast furnace is lower than the standard. There is a risk of gas explosion if the gas system is connected without gas explosion test and confirmation that there will be no explosion.

　　■ if the furnace top and throat are not ignited when the wind is off for a long time (≥ 4 hours), there is a risk of poisoning, suffocation and gas explosion.

　　■ before and during the wind break, if there is any damage that is not replaced in time or effective measures are taken, there is a risk of water leakage into the furnace and furnace explosion.

　　Blast furnace body

　　■ all materials in the furnace are in a high temperature and reducing atmosphere of 1150 ℃ ~1450 ℃, and the reduction reaction is carried out during the melting process. Improper operation may cause explosion. High temperature melt may explode due to violent vaporization in case of furnace sleeve rupture and water leakage.

　　■ molten iron mixed with water and slag flushing system may cause explosion.

　　■ during the smelting process, the blast furnace has been used for a long time without timely maintenance, resulting in damage to the refractory layer, which may cause the furnace bottom to burn through and the molten iron to flow out and explode.

　　■ the cooling stave cannot guarantee the cooling water supply, which may cause the furnace bottom to burn through and the molten iron to flow out and cause explosion

　　■ the water test device at the furnace base, bottom, hearth and other parts is damaged, resulting in inaccurate furnace temperature test or untimely furnace temperature test, which may lead to blast furnace burning through molten iron outflow.

　　■ the cracking of furnace body and shell occurs longitudinal or radial cracks due to thermal expansion exceeding the limit, resulting in gas leakage and air mixing to form an explosive mixture. The leaked high-temperature gas has ignition energy and can explode.

　　■ there is ponding around the furnace base, which may cause molten iron explosion

　　■ there is leakage in the cooling parts, and there is a risk of molten iron explosion.

　　■ before overhauling the blast furnace and discharging the residual iron, the operation platform was not set up to completely remove the ponding around the furnace foundation, which may cause the risk of residual iron explosion.

　　■ the blast furnace is suddenly cut off, and the blast is not shut down according to the emergency shut down procedure. Gas leakage may occur, resulting in gas poisoning, suffocation, combustion and explosion.

　　■ water supply is not carried out in sections and quickly, which may produce a large amount of steam and cause explosion

　　■ for water cut-off accident treatment, the water inlet valve is too fast, resulting in sudden cooling of the cooling equipment or sudden generation of a large amount of steam and explosion.

　　■ the blast furnace has a long suspension time, a large space is formed in the furnace, and the furnace top temperature gradually rises beyond the specified value, which may draw water to cool down and produce a large amount of steam. When the charge column collapses, the furnace top will instantly generate negative pressure, and the air and the cold material mixed with gas will enter the furnace. The upper and lower density are not strict. In case of high-temperature gas, the furnace top may explode.

　　Dedusting system of hot blast stove

　　■ the gas main pipe of hot blast stove is not provided with reliable isolating device according to the requirements of GB 6222. The gas branch pipe is not equipped with a gas automatic shut-off valve. When the burner fan stops running, or the combustion air shut-off valve is closed, or the gas pressure is too low, the shut-off valve cannot automatically cut off the gas and does not give an alarm. Gas pipeline is not equipped with gas flow detection and regulation device. There is no gas release pipe at the highest part of the pipeline and between the combustion valve and the gas shut-off valve, so there is a risk of combustion explosion, poisoning and suffocation.

　　■ hot blast stove pipes and various valves are not tight. The necessary safety interlock is not set between the hot blast stove and the blower station or between each part of the hot blast stove. In case of sudden power failure, the valve will not automatically switch to the safe direction, and there is a risk of combustion and explosion.

　　■ the cut-off valve is not set before the air mixing regulating valve of the hot blast stove. Once the blast furnace air pressure is less than 0.05 MPa, if the air mixing cut-off valve is not closed, there is a risk of combustion and explosion.

　　■ during the hot blast stove burning, when the flame goes out, the gas gate is not closed in time and the ignition is not started again, which is dangerous for explosion.

　　■ blast furnace gas is required to be used as fuel for combustion and heating in the heating furnace for hot blast stove and gas supply pipe network. If the blast furnace gas supply and combustion system is improperly operated or gas leaks, explosion may occur.

　　■ during production and equipment maintenance, relevant safety operation requirements shall be followed. The gas in the dust collector may cause fire, explosion and poisoning accidents.

　　■ for the gas purification bag type dust removal system, the top temperature of the blast furnace rises abnormally, exceeding the pipeline expansion compensation capacity, causing pipeline rupture and gas leakage, resulting in fire, explosion and poisoning accidents.

　　■ the maintenance of the blast furnace dust removal system requires nitrogen purging. If nitrogen is not set, incomplete purging may lead to poisoning or fire and explosion accidents.

　　Blast furnace gas system

　　■ there is a negative pressure in the gas pipeline, and there is an explosion risk when the gas pipeline enters the air.

　　■ if the gas system is not equipped with safety devices such as low-pressure alarm, quick cut-off and release devices, it may cause gas leakage, fire explosion or personnel poisoning and suffocation accidents.

　　■ the dust collector is not equipped with a steam or nitrogen pipe head with a cock, or its steam pipe or nitrogen pipe is not connected with the steam drum of the furnace platform, or is blocked or frozen, which may cause combustion explosion, poisoning and suffocation.

　　Ironmaking yard and furnace platform structure in front of furnace

　　■ molten iron explosion may occur due to illegal operation and use of wet tools in the process of opening, tapping, slag tapping and iron plugging.

　　■ there is accumulated water on the iron ditch or platform. Once the iron overflows, the iron explosion may occur.

　　■ molten iron explosion may occur if the slag skimmer is burned through or damaged, the iron mouth is wet, and there is iron in the slag.

　　Cast iron machine

　　■ there shall be no ponding in the cast iron machine pit. Otherwise, molten iron explosion accident may be caused