Hot air furnace effective technical measures to improve the air temperature

Hot air furnace effective technical measures to improve the air temperature

1. Raise the theoretical combustion temperature of hot air furnace.

This is the key to getting high wind temperatures. The main measures available are:

(1) enrich blast furnace gas and increase gas calorific value. Generally speaking, for every 1% increase of coke oven gas, the low calorific value of mixed gas increases by 125 ~ 138KJ/m3, and the hot air temperature can increase by about 15℃.

(2) increase the preheating temperature of gas and combustion air, that is, increase the physical sensible heat brought in by air and gas. The heating value of preheating air gas is better than that of enriching gas. At present, the existing preheating furnace technology and hot air furnace self-preheating technology are based on this as a starting point to preheat the combustion air in different ways, can improve the temperature of hot air furnace.

(3) oxygen-rich combustion is adopted to reduce the amount of smoke generated. Oxygen-rich combustion is a highly efficient and energy-saving combustion technology, which can effectively reduce the excess air coefficient, reduce the amount of smoke, increase the theoretical combustion temperature, and increase production and coke saving efficiency under the same conditions. However, the oxygen-rich flow rate cannot increase indefinitely, otherwise the amount of smoke gas is too little to meet the thermal requirements of lattice brick, will lose more than it pays.

2. Adopt the hot air piping system with reasonable lining, low stress and directional expansion.

This is very important for high temperature longevity hot air furnace. The hot air pipeline is affected by the high temperature of the blast furnace for a long time due to the periodic changes. In order to reduce the impact of stress on the pipeline, it is necessary to set compensators on both sides of the hot air branch pipe and the upper branch pipe of the main pipe. The pipe is subject to limited directional expansion by such measures as setting guide and fixed support; At the same time to ensure that these facilities do not affect the pipeline valve installation and maintenance work. Generally, the working layer of the pipeline is made of aluminum with high heat resistance, low creep rate and good thermal shock resistance. The composite brick masonry structure should be adopted in the key parts such as the hot air pipe mouth and three branches. Meanwhile, the heat insulation and insulation of the pipeline should be paid attention to to ensure the stability and air tightness of the overall lining.

3. Adopt the structure of top-burning hot air furnace.

Compared with the internal combustion hot air furnace, the heat storage area can be increased by 25% ~ 30% under the same capacity. The distribution of airflow in the furnace is uniform, the heat transfer is symmetrical, the uniformity is good, the thermal efficiency is high, so the hot air temperature is high; At the same time, it also avoids the disadvantages of large area and high investment cost of external combustion hot air furnace. The practice has proved that the high wind temperature can be realized with the low dome temperature, the working condition of refractory material is improved obviously, and the high wind temperature and long life can be achieved at the same time.

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