Firstly, the regenerative effect of the combustion chamber and the upper bed of the hot blast stove is poor. The specific performance is that the temperature of the combustion chamber rises slowly while burning the stove. When the temperature of the combustion chamber reaches 1200 C, the flue temperature is already high and the stove can not continue burning, otherwise the flue temperature exceeds the standard and a lot of fuel is wasted. But at this time, the heat storage of the combustion chamber and the upper bed of the hot blast stove is limited. After stopping the oven, the temperature of the combustion chamber drops rapidly, which requires frequent burning.
2. The temperature distribution in the furnace bed is extremely uneven, and the temperature in the conversion zone is too low. The silica brick wall and the silica brick furnace bed in this area are liable to be damaged.
The conversion area refers to the transition area from the silica brick hearth to the high alumina brick hearth.
When the hot stove is kept warm, it can only burn at low load, and the high load furnace will cause the flue temperature to run out of control. Liquefied petroleum gas (LPG) low-load burner has a very small amount of flue gas. Hot flue gas quickly reaches the hearth from the upper burner along the central axis of the hot blast stove, which makes it difficult to cover the whole hearth. As a result, the temperature of the hearth is higher in the central part of the hearth, but it is difficult to raise the temperature near the hearth wall. During the long-term heat preservation process, the temperature of the transition zone near the hearth wall keep Or even below 600 degrees Celsius. 570~600 C is the phase transition temperature range of silica brick, and the temperature below this temperature will damage the silica brick. When the blast furnace is resumed for the first time, the transition zone near the furnace wall will fall to a lower temperature. When the gas is normal, the furnace will be burned with heavy load. At this time, the temperature of the conversion zone near the furnace wall will rise sharply from 550 C. This is the most taboo condition of the silica brick furnace bed and the silica brick furnace wall. This will most likely cause damage to silica brick, which will affect the permeability of hot blast stove hearth or cause structural damage to furnace wall.
Three. Excessive fuel consumption and high cost of heat preservation.
Because the burner of hot blast stove is designed based on the physical and chemical parameters of blast furnace gas, the structure of burner can not be changed, so it is difficult to adjust the combustion condition to the ideal state when converting to LPG thermal insulation burner. This is the main reason causing poor heat storage and uneven temperature distribution in hot blast stove. In order to ensure the basic temperature of the hot blast stove, it is necessary to burn the stove frequently and waste fuel. Because the combustion condition is not ideal, it is easy to cause incomplete combustion, and also cause fuel waste and safety hazards.
Four. Incomplete combustion may cause high temperature in the middle of the hearth.
Because of the uneven temperature distribution, the higher temperature in the central part of the hot blast stove and the lower temperature in the wall part of the thermometer, the actual temperature in the central area may be much higher than the measured temperature of the combustion chamber thermometer. Liquefied petroleum gas (LPG) has a very high calorific value, which is 35 times higher than blast furnace gas. When incomplete combustion occurs, it may cause the actual temperature in the central area of hot blast stove to reach more than 1500 C, but the combustion chamber thermometer can not measure it.
The temperature of the local hearth is too high, resulting in the softening and deforming of the checker brick, which seriously affects the air permeability of the hot stove. A hot blast stove in a foundry in Guangdong Province had to be rebuilt after removing the upper grate brick.
The main reason for the above bad conditions is that the combustion condition of the stove after changing the fuel is not good. How to make liquefied petroleum gas (LPG) can be scientifically matched with the burner of hot blast stove is the key to solve the problem. Blind use of liquefied petroleum gas (LPG) for long-term heat preservation of hot blast stove may cause great damage to lattice bricks and silica brick walls of hot blast stove bed.
It is difficult to use liquefied petroleum gas (or liquefied natural gas) for hot-blast stove burning. It needs professional technicians who really know how to implement it in order to achieve the effect of safety, reliability, protection and cost reduction.
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