High-humidity flue gas energy efficient utilization method based on quick lime digestion process

Abstract

The invention discloses a quick lime digestion process-based high-humidity flue gas energy efficient utilization method, which comprises the following steps of: introducing high-temperature and high-humidity flue gas into a digester for digestion reaction, removing moisture from the digested flue gas, raising the temperature of the flue gas to 170-190 DEG C, returning the high-temperature and low-humidity flue gas to a hot blast stove through a circulating system, high-temperature low-humidity flue gas reduces gas consumption of the hot-blast stove. The high-humidity flue gas is dehydrated by using a quick lime digestion process, so that water consumption required by quick lime digestion can be reduced, moisture in the high-humidity flue gas can be removed, the temperature of the flue gas is increased by 70 DEG C or above, the dehumidified high-temperature flue gas is used for combustion of a hot blast stove or coal gas preheating and other links, and coal gas consumption is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of comprehensive utilization of high-humidity flue gas dried by pre-iron raw materials, and in particular to a method for efficiently utilizing high-humidity flue gas energy based on a quicklime slaking process. Background Art

[0002] During steel smelting, the ore powder is ground in the vertical mill and dried by hot flue gas. Qualified ore powder enters the powder collector together with the hot exhaust gas for collection. The hot exhaust gas with high humidity is discharged through the chimney through the induced draft fan, and the rest returns to the hot blast furnace for recycling.

[0003] However, the temperature of the high-humidity flue gas discharged from the drying of raw materials is generally around 100°C, and the humidity of the flue gas is high. The external discharge causes the loss of heat energy and water resources and cannot be comprehensively utilized. In addition, the flue gas circulating into the hot blast furnace has a high water content, which wastes coal gas. Therefore, it is necessary to develop a new high-humidity flue gas energy efficient utilization method to overcome the above problems. Summary of the invention

[0004] Purpose of the invention: In view of the shortcomings and defects of the prior art, the present invention provides a method for efficiently utilizing high-humidity flue gas energy based on the quicklime digestion process. The quicklime digestion process is used to dehydrate this part of the high-humidity flue gas, which can save the water consumption required for quicklime digestion. At the same time, it can also remove moisture from the high-humidity flue gas and increase the flue gas temperature by more than 70°C. The high-temperature flue gas after dehumidification is used for hot blast furnace combustion or preheating of coal gas, saving coal gas consumption.

[0005] Technical solution: The invention discloses a method for efficiently utilizing high-humidity flue gas energy based on quicklime digestion process, which is characterized in that: high-temperature and high-humidity flue gas is passed into a digester for digestion reaction, moisture is removed from the digested flue gas, the flue gas temperature is increased to 170°C-190°C, and the high-temperature and low-humidity flue gas is returned to the hot blast furnace through a circulation system, so that the high-temperature and low-humidity flue gas reduces the gas consumption of the hot blast furnace.

[0006] During the digestion reaction, quicklime from a quicklime bin (8) is sprayed into the high-temperature and high-humidity flue gas to dehumidify the flue gas.

[0007] Among them, bag dust removal is used to collect particulate matter in the flue gas after the quicklime is sprayed, and the collected slaked lime is transported to the desulfurization slaked lime silo through a pipeline for standby use.

[0008] The high-temperature, low-humidity flue gas is transported to the hot blast furnace to replace the combustion-supporting air at room temperature to participate in combustion, and the excess high-temperature flue gas is used to preheat the blast furnace gas and participate in the circulating air of the grinding system.

[0009] Wherein, the digester is connected with the chimney, quicklime bin and desulfurization slaked lime bin through separate pipelines respectively.

[0010] Wherein, the digester is connected to the hot air furnace through a recycling pipeline.

[0011] Wherein, the digester is connected to the powder collector through a pipeline provided with an induced draft fan.

[0012] Wherein, the powder collector is connected to the vertical mill.

[0013] Wherein, the vertical mill is connected to the silo via a feed screw.

[0014] Wherein, the vertical mill is connected to a hot blast furnace.

[0015] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: the present invention utilizes the high-humidity saturated flue gas discharged during the vertical roller mill dry grinding production process to pre-digest the quicklime of the desulfurization process, and the high-temperature flue gas after dehumidification participates in the combustion of the hot blast furnace and the use of the system circulating air, which effectively solves the waste of heat energy and water resources caused by the direct discharge of high-humidity flue gas. At the same time, the quicklime can also be digested, reducing the water consumption of the quicklime digestion process and significantly reducing the gas consumption of dry grinding. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the prior art;

[0017] Figure 2 It is a structural schematic diagram of the present invention;

[0018] In the figure, 1 is a silo; 2 is a feed screw; 3 is a vertical mill; 4 is a hot air furnace; 5 is a powder collector; 6 is an induced draft fan; 7 is a chimney; 8 is a quicklime silo; 9 is a digester; and 10 is a desulfurized slaked lime silo. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0020] The high-humidity flue gas energy efficient utilization method based on the quicklime digestion process of the present invention is to pass the high-temperature and high-humidity flue gas into the digester 9 for digestion reaction, remove moisture from the digested flue gas, and increase the flue gas temperature to 170°C-190°C. The high-temperature and low-humidity flue gas returns to the hot blast furnace 4 through the circulation system, and the high-temperature and low-humidity flue gas reduces the gas consumption of the hot blast furnace 4. During the digestion reaction, quicklime from the quicklime bin 8 is sprayed into the high-temperature and high-humidity flue gas to dehumidify the flue gas. The particulate matter in the flue gas after the quicklime is sprayed is collected by bag dust removal, and the collected slaked lime is transported to the desulfurization slaked lime bin 10 through a pipeline for standby. The high-temperature and low-humidity flue gas is transported to the hot blast furnace 4 to replace the combustion-supporting air at normal temperature to participate in combustion, and the excess high-temperature flue gas is used to preheat the blast furnace gas and participate in the circulating air of the grinding system.

[0021] The digester 9 of the present invention is connected to the chimney 7, the quicklime bin 8, and the desulfurized lime bin 10 through separate pipelines. The digester 9 is connected to the hot blast furnace 4 through a recycling pipeline. The digester 9 is connected to the powder collector 5 through a pipeline provided with an induced draft fan 6. The powder collector 5 is connected to the vertical mill 3. The vertical mill 3 is connected to the silo 1 through a feed screw 2. The vertical mill 3 is connected to the hot blast furnace 4.

[0022] The present invention realizes the functions of high-temperature and high-humidity flue gas dehydration and flue gas heating, and the flue gas temperature can be increased by 70℃-90℃; and the comprehensive utilization of medium-low temperature flue gas (170-190℃) after dehumidification is realized. The present invention efficiently recycles the heat and moisture in the hot exhaust gas; reduces the water resource consumption in the quicklime digestion reaction process; utilizes the heat energy of high-temperature flue gas, can reduce the system flue gas volume, and can reduce the fan configuration, so as to save electricity consumption.

[0023] According to calculation, the present invention can generate the following economic benefits:

[0024] Direct economic benefits: high-temperature flue gas is involved in combustion and recycling, and 0.15GJ of coal gas is saved for drying a ton of iron material, equivalent to 40m3 of blast furnace gas 3 / ton of ore, 40 tons of industrial clean water per hour, based on the calculation of drying 4 million tons of iron ore per year and 10% water content of iron material, blast furnace gas consumption can be saved by 160 million m 3 , comprehensive utilization of water 400,000 tons, according to blast furnace gas 0.1 yuan / m 3 , calculated at 2.6 yuan for industrial clean water, the all-energy gas consumption cost is saved by 16 million yuan, the industrial clean water is saved by 1.04 million yuan, and the total system energy saving is 17 million yuan per year.

[0025] Indirect economic benefits: Reduce water resource consumption. At the same time, due to the utilization of high-temperature flue gas heat energy, the system flue gas volume can be reduced, the fan configuration can be reduced, and electricity consumption can be saved.

Claims

1. A method for efficiently utilizing high-humidity flue gas energy based on quicklime digestion process, characterized in that: The high-temperature and high-humidity flue gas is introduced into the digester (9) for digestion reaction. The water content of the digested flue gas is removed and the flue gas temperature is increased to 170°C-190°C. The high-temperature and low-humidity flue gas is returned to the hot blast furnace (4) through the circulation system. The high-temperature and low-humidity flue gas reduces the gas consumption of the hot blast furnace (4).

2. The method for efficiently utilizing high-humidity flue gas energy based on quicklime digestion process according to claim 1 is characterized in that: During the digestion reaction, quicklime from the quicklime bin (8) is sprayed into the high-temperature and high-humidity flue gas to dehumidify the flue gas.

3. The high-humidity flue gas energy efficient utilization method based on quicklime digestion process according to claim 2 is characterized in that: The particulate matter in the flue gas after the quicklime is sprayed is collected by using a bag filter, and the collected quicklime is transported to the desulfurization quicklime bin (10) through a pipeline for standby use.

4. The method for efficiently utilizing high-humidity flue gas energy based on quicklime digestion process according to claim 3 is characterized in that: The high-temperature, low-humidity flue gas is transported to the hot blast furnace (4) to replace the combustion-supporting air at room temperature to participate in combustion, and the excess high-temperature flue gas is used to preheat the blast furnace gas and participate in the circulating air of the grinding system.

5. The method for efficient utilization of high-humidity flue gas energy based on quicklime digestion process according to claim 4 is characterized in that: The digester (9) is connected to the chimney (7), the quicklime bin (8) and the desulfurized slaked lime bin (10) through separate pipelines.

6. The method for efficient utilization of high-humidity flue gas energy based on quicklime digestion process according to claim 5 is characterized in that: The digester (9) is connected to the hot blast furnace (4) via a recycling pipeline.

7. The method for efficient utilization of high-humidity flue gas energy based on quicklime digestion process according to claim 6 is characterized in that: The digester (9) is connected to the powder collector (5) via a pipeline provided with an induced draft fan (6).

8. The method for efficient utilization of high-humidity flue gas energy based on quicklime digestion process according to claim 7 is characterized in that: The powder collector (5) is connected to the vertical mill (3).

9. The method for efficient utilization of high-humidity flue gas energy based on quicklime digestion process according to claim 8, characterized in that: The vertical mill (3) is connected to the silo (1) via a feed screw (2).

10. The method for efficient utilization of high-humidity flue gas energy based on quicklime digestion process according to claim 9, characterized in that: The vertical mill (3) is connected to a hot air furnace (4).

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