Method for reducing coal gas consumed by burning of blast furnace hot blast stove

Abstract

The invention relates to a method for reducing combustion gas consumption of a blast furnace hot blast stove, which comprises the following steps: S1, after the hot blast stove is converted from air supply to combustion, firstly, quickly increasing the temperature of a vault according to a specified gradient, and after ignition with smaller gas and air flows, gradually increasing the gas flow and the air flow to achieve the optimal flow required by normal combustion; s2, the coal gas flow and the air flow are adjusted, the air-fuel ratio reaches 1.05, and the vault temperature continues to rise; and S3, after the temperature of the vault reaches 1370 DEG C, the air-fuel ratio is adjusted again, and in combination with the change of the temperature of the flue, when the temperature of the flue is about 360-400 DEG C, the coal gas consumption is started to be reduced, meanwhile, it is guaranteed that the temperature of the vault is maintained at 1320-1400 DEG C, and when the temperature of the flue is increased by 8-12 DEG C, the coal gas amount is continuously reduced until furnace burning is finished. Gas combustion efficiency and hot-blast stove heat efficiency can be improved, so that gas usage amount of the hot-blast stove is saved, ironmaking cost is reduced, economic benefits are improved, and environmental pollution is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of ironmaking, and particularly relates to a method for reducing the gas consumption of a blast furnace hot blast stove during firing. Background Art

[0002] The hot blast stove is an important heat exchange device in the blast furnace smelting process, and its function is to heat the blast air to the temperature required for blast furnace smelting. If the firing technology is not taken seriously and the gas consumption of the hot blast stove remains high, it will lead to a waste of gas energy.

[0003] The traditional method of firing a blast furnace hot blast stove is to use rapid combustion with a large air volume and a large gas volume at the initial stage to make the arch top temperature reach the set value. In the middle and later stages, during the process of increasing the flue gas temperature, according to the requirements of the air supply time, the gas volume is reduced several times. This firing method is likely to cause a large amount of gas consumption at the initial stage, a large waste gas flow rate, a high flow velocity, a low heat utilization rate of the combustion waste gas, and a rapid increase in the flue gas temperature of the flue. During the process of reducing the gas, it is necessary to repeatedly adjust the gas volume and the air-fuel ratio, and it is very difficult to control the air-fuel ratio to the optimal value. This situation is likely to result in a low combustion thermal efficiency of the hot blast stove and a large gas consumption. Summary of the Invention

[0004] In view of the above problems, the purpose of the present invention is to provide a method for reducing the gas consumption of a blast furnace hot blast stove during firing, which can effectively improve the gas combustion efficiency and the thermal efficiency of the hot blast stove, and save the gas usage of the hot blast stove.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A method for reducing the gas consumption of a blast furnace hot blast stove during firing proposed by the present invention specifically includes the following steps:

[0007] S1. After the hot blast stove is switched from air supply to combustion, first make the arch top temperature rise rapidly according to a specified gradient. After igniting with a relatively small gas and air flow rate, gradually increase the gas flow rate and the air flow rate to reach the optimal flow rate required for normal combustion;

[0008] S2. Adjust the gas and air flow rates so that the air-fuel ratio reaches 1.05, and make the arch top temperature continue to rise;

[0009] S3. When the arch top temperature reaches 1370 °C, adjust the air-fuel ratio again. Combining with the change of the flue gas temperature, when the flue gas temperature is about 360 - 400 °C, start to reduce the gas usage, and at the same time ensure that the arch top is maintained at 1320 - 1400 °C. When the flue gas temperature rises by 8 - 12 °C, continue to reduce the gas volume until the firing ends.

[0010] Further, the entire process of step S1 lasts for no more than 20 minutes. During this period, the arch top temperature rises rapidly and approaches the highest temperature.

[0011] The present invention has the following beneficial effects compared with the prior art:

[0012] The present invention can effectively improve the gas combustion efficiency and the thermal efficiency of the hot blast stove, thereby saving the gas consumption of the hot blast stove, reducing the ironmaking cost, increasing the economic benefits, and reducing environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic structural diagram of an existing blast furnace hot blast stove.

[0014] Among them, reference numerals: 1 - air inlet; 2 - gas inlet; 3 - flue. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0016] In the initial stage of the firing combustion of the blast furnace hot blast stove, increase the gas volume and air volume in several steps, adjust the optimal air-fuel ratio, so that the arch top temperature quickly reaches the set value. In the middle and late stages of firing, while ensuring that the arch top temperature remains at the set value, the gas consumption gradually decreases, the air-fuel ratio is easy to control stably and reasonably, the flue temperature continues to rise according to the set temperature, and the arch top temperature is stable. This method, taking the premise that the arch top temperature and the waste gas temperature reach the set values in each stage of firing, distributes the gas consumption more reasonably and stably, improves the gas combustion efficiency and the thermal efficiency of the hot blast stove, saves the gas consumption of the hot blast stove, reduces the ironmaking cost, and increases the economic benefits.

[0017] A method for reducing the gas consumption in the firing of a blast furnace hot blast stove proposed by the present invention specifically includes the following steps:

[0018] S1. After the hot blast stove is switched from air supply to combustion, first make the arch top temperature rise rapidly according to a specified gradient. After igniting with a small gas and air flow rate, gradually increase the gas flow rate and air flow rate to reach the optimal flow rate required for normal combustion. The duration of this process does not exceed 20 minutes. During this period, the arch top temperature rises rapidly and approaches the highest temperature.

[0019] S2. Adjust the gas and air flow rates so that the air-fuel ratio reaches 1.05, and make the arch top temperature continue to rise. The heat exchange between the high-temperature waste gas and the checker bricks in the regenerator intensifies, and the temperature of the checker bricks rises rapidly. As the temperature of the regenerator rises, the waste gas temperature reaches above 350 °C.

[0020] S3. After the vault temperature reaches 1370 °C, adjust the air-fuel ratio again. Considering the change in the flue gas temperature, when the flue gas temperature is between 360 - 400 °C, start to reduce the gas consumption, and at the same time ensure that the vault temperature is maintained between 1320 - 1400 °C. When the flue gas temperature rises by 8 - 12 °C, continue to reduce the gas volume until the end of the furnace firing.

[0021] The present invention specifically divides the furnace firing of the blast furnace hot blast stove into several stages. In the initial stage, increase the gas volume and air volume step by step, and adjust the optimal air-fuel ratio to quickly reach the set value of the vault temperature, laying a foundation for the subsequent heat storage of the furnace body. In the middle and late stages, while ensuring that the vault temperature remains at the set value, gradually reduce the gas consumption, and synchronously adjust the air consumption according to the air-fuel ratio, so that the flue gas passes through the furnace body to make the flue gas temperature continuously rise according to the set temperature. The high-temperature flue gas completes the heat exchange with the heat storage body installed inside the hot blast stove, avoiding the unreasonable use of air and gas from affecting the heat transfer and heat storage effect, thereby improving the gas combustion efficiency and the thermal efficiency of the hot blast stove, and saving the gas consumption of the hot blast stove.

[0022] Matters not detailed in the present invention are all well-known technologies.

[0023] The embodiments described above are only used to describe the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for reducing the consumption of gas in the stoves of blast furnaces, characterized in that, The method includes the following steps: S1. After the hot blast stove switches from air supply to combustion, first make the vault temperature rise rapidly according to a specified gradient. After ignition with a small gas and air flow rate, gradually increase the gas flow rate and air flow rate to reach the optimal flow rate required for normal combustion; S2. Adjust the gas and air flow rates so that the air-fuel ratio reaches 1.05 and make the vault temperature continue to rise; S3. After the vault temperature reaches 1370 °C, adjust the air-fuel ratio again. Considering the change in the flue gas temperature, when the flue gas temperature is around 360 - 400 °C, start to reduce the gas consumption, and at the same time ensure that the vault temperature is maintained between 1320 - 1400 °C. When the flue gas temperature rises by 8 - 12 °C, continue to reduce the gas volume until the end of the furnace burning.

2. A method for reducing the consumption of gas in the stove burning process of a blast furnace hot blast stove according to claim 1, characterized in that: The entire process of step S1 lasts no more than 20 minutes. During this period, the vault temperature rises rapidly and approaches the highest temperature.

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