CN103484580A - Method and device for recovering molten blast furnace slag sensible heat - Google Patents

Abstract

The invention belongs to the technical field of energy recovery, and particularly relates to a method and device for recovering the sensible heat of molten blast furnace slag. The air is blown in from the bottom of the bottom-blowing composite molten slag ditch, and the regenerator is heated to 1100-1250°C at this time; 2) The slag whose temperature has been lowered to 700-800°C enters the old slag treatment system through the connecting unit. The slag is used for subsequent treatment; 3) When the blast furnace stops slag discharge, the bottom of the bottom-blown composite molten slag ditch is still blown into air, and the air is heated to 800-900°C during the process of passing through the heat storage body; 4) The hot air is dedusted After that, it is used to generate electricity, and the cooling water replaces heat for production. Compared with the prior art, the beneficial effect of the present invention is: through the transformation, the heat energy can be efficiently recovered and the temperature of the combustion-supporting air of the hot blast stove can be increased, and the waste heat can also be used for power generation to achieve the purpose of energy reuse.

Description

A method and device for recovering sensible heat from molten blast furnace slag

technical field

The invention belongs to the technical field of iron and steel metallurgy energy saving and emission reduction and secondary energy recovery, and in particular relates to a method and a device for recovering sensible heat of molten blast furnace slag.

Background technique

The iron and steel industry is an important basic industry of my country's national economy. Since the 1990s, my country's iron and steel industry has developed rapidly. In 2012, the output of crude steel reached 720 million tons, of which the output of blast furnace pig iron (that is, long-process crude steel production) was close to 659 million tons. , with the growth of iron and steel production, the total amount of solid waste produced by the iron and steel industry is increasing. Among the solid waste, blast furnace slag accounts for a large proportion. Blast furnace slag emissions vary with ore grade and smelting method. Generally speaking, when the charge grade reaches 60% to 66%, 250 to 300 kilograms of slag will be produced for every ton of pig iron smelted. Based on this calculation, the annual blast furnace slag output in my country is also about 165 to 198 million tons.

At the same time, the energy consumption of the steel industry accounts for 10% to 15% of the country's total energy consumption. At present, the main steel production process is a long process, including coking process, sintering process, blast furnace ironmaking process, converter steelmaking process and steel rolling process. , while the resource and energy consumption of the blast furnace ironmaking process is the largest, accounting for about 77% of the entire iron and steel production process. The temperature of blast furnace slag is generally 1400℃～1500℃, that is, the heat contained in 1 ton of blast furnace slag is equivalent to 64kg of standard coal. In this way, the heat taken away by blast furnace slag in my country is equivalent to 1056～1267.2 tons of standard coal every year.

At present, the sensible heat utilization rate of blast furnace slag in my country is extremely low, and most enterprises adopt water slag treatment process, and the so-called utilization means that northern enterprises use blast furnace slag flushing water for heating in winter, due to the limitation of heating area, flow rate and other conditions, and The slag flushing water contains a large amount of alkaline substances, which will cause corrosion of pumps and pipelines. The utilization rate of slag heat energy is extremely low, and it cannot adapt to the three seasons of spring, summer, and autumn. A large amount of hot water and steam affect production. Therefore, the recovery of sensible heat from blast furnace slag is a very important issue and needs to be solved urgently.

Contents of the invention

The purpose of the present invention is to provide a method and device for recovering the sensible heat of molten blast furnace slag. Under the premise of not changing most of the existing blast furnace water slag flushing process, the sensible heat of blast furnace slag can be recovered by reforming the molten slag ditch , The purpose of energy reuse.

In order to solve the problems of the technologies described above, the technical solution of the present invention is:

A method for recovering the sensible heat of molten blast furnace slag, the process of which is carried out in sequence as follows: 1) Blast furnace slag with a temperature of 1400-1500 °C enters the sectioned bottom-blown composite molten slag ditch, and simultaneously compresses 1.5-2.0 MPa The air is blown in from the bottom of the bottom-blown composite molten slag ditch at a speed of 8-10 m/s, stirring the slag while ensuring the fluidity of the slag, realizing the radiant heat absorption of the regenerative masonry on the top of the bottom-blown composite molten slag ditch, At this time, the regenerator is heated to 1100-1250°C; 2) The slag whose temperature has been lowered to 700-800°C enters the old slag treatment system through the connection unit for subsequent treatment of the slag; 3) When the blast furnace stops discharging When slag is slag, the bottom of the bottom-blown composite molten slag ditch is still blown into air, and the air is heated to 800-900°C during the process of passing through the heat storage body; 4) After the hot air is dedusted, it is introduced into the waste heat power generation boiler for power generation. Cooling water is used for production by displacing heat through a heat exchanger.

After the hot air is dedusted, it can also be used as the combustion-supporting air of the hot stove.

The bottom-blown composite molten slag ditch is characterized in that it includes a cement outer slag ditch, a ditch body support, a ditch body and a ditch cover, the bottom of the cement outer slag ditch is provided with a ditch body support, and the upper part of the ditch body support is provided with a refractory material The ditch body and ditch cover are made, the inner surface of the ditch cover is provided with heat storage masonry, the slag flow channel is surrounded between the ditch body and the ditch cover, the bottom of the ditch body is provided with a copper stave, and the copper stave is equipped with a cooling The bottom of the copper stave is provided with a bottom blowing air pipe, and the bottom blowing air pipe is provided with a blowing pipe to communicate with the slag flow channel upwards.

Compared with prior art, the beneficial effect of the present invention is:

This method can not only effectively recover the sensible heat of molten blast furnace slag, but also can make full use of the existing slag treatment system. Through the partial transformation of the blast furnace casthouse, it can not only recover heat energy efficiently but also increase the temperature of the combustion air of the hot blast stove, and can also be used for waste heat. Generate electricity to achieve the purpose of energy reuse.

Description of drawings

Fig. 1 is a schematic structural view of an embodiment of a bottom-blown composite molten slag ditch of the present invention;

Fig. 2 is a schematic diagram of one of the implementation processes of the present invention;

Fig. 3 is a schematic diagram of the second implementation process of the present invention.

In the figure: 1-cement outer slag ditch 2-ditch body support 3-ditch body 4-ditch cover 5-heat storage masonry 6-slag runner 7-copper stave 8-cooling water pipe 9-bottom blowing air pipe 10 -Injection pipe 11-Blast furnace 12-Bottom blowing compound molten slag ditch 13-Connection unit 14-Heat exchanger 15-Waste heat power generation boiler 16-Dust collector

Detailed ways

The specific embodiment of the present invention will be further described below in conjunction with accompanying drawing:

See Fig. 1, which is a structural schematic diagram of an embodiment of the bottom-blowing composite molten slag ditch of the present invention, including a cement outer slag ditch 1, a ditch body support 2, a ditch body 3 and a ditch cover 4, and the bottom of the cement outer slag ditch 1 is provided with a ditch body support 2. The upper part of the trench body support 2 is provided with a trench body 3 and a trench cover 4 made of refractory materials. The inner surface of the trench cover 4 is provided with a heat storage masonry 5, and a slag is formed between the trench body 3 and the trench cover 4 The flow channel 6, the bottom of the ditch body 3 is provided with a copper stave 7, the copper stave 7 is provided with a cooling water pipe 8, the bottom of the copper stave 7 is provided with a bottom blowing air pipe 9, and the bottom blowing air pipe 9 is provided with a blowing pipe 10 It communicates with the slag runner 6 upwards. The cooling water pipe 8 is connected to the heat exchanger for heat recovery, and the bottom blowing air pipe 9 is connected to the blower. According to the physical characteristics of the molten blast furnace slag: slow heat transfer speed, and the viscosity rises sharply with the decrease of temperature, etc., the blowing pipe 10 should be arranged reasonably Quantity and location, so that the radiant heat of molten blast furnace slag can be absorbed by the regenerator and maintain proper fluidity.

See Figure 2, which is a schematic diagram of one of the implementation processes of a method for recovering the sensible heat of molten blast furnace slag according to the present invention. The radiant heat of molten blast furnace slag is absorbed through the bottom-blown composite molten slag ditch, and heat exchange generates hot air and hot water. To achieve the purpose of recovery of sensible heat from blast furnace slag, 1) First, the blast furnace slag discharged from the blast furnace 11 with a temperature of 1400-1500°C enters the sectioned bottom-blowing composite molten slag ditch 12, and at the same time, the compressed air of 1.5-2.0 MPa is injected at 8 The speed of ~10 m/s is blown from the bottom of the bottom-blown composite molten slag ditch, and the slag is stirred while ensuring the fluidity of the slag, so as to realize the radiant heat absorption of the thermal storage masonry on the top of the bottom-blown composite molten slag ditch. The heating body is heated to 1100-1250°C, and the air blown in from the bottom is also above 900°C at the outlet; 2) Secondly, the slag whose temperature has been lowered to 700-800°C enters the old slag treatment system through the connection unit. The slag is used for follow-up treatment; 3) When the blast furnace stops slag discharge, air is still blown into the bottom of the bottom-blown composite molten slag ditch, and the air is heated to 800-900°C during the process of passing through the regenerator; 4) Finally, the slag The cooling water (about 80°C) of the ditch passes through the heat exchanger 14 to replace the heat for production, while the hot air is dedusted and introduced into the waste heat power generation boiler 15 for power generation. In the figure, the front stage of the waste heat power generation boiler has a dust removal device.

See Figure 3, which is a schematic diagram of the second implementation process of a method for recovering sensible heat from molten blast furnace slag according to the present invention. The radiant heat of molten blast furnace slag is absorbed through the bottom-blown composite molten slag ditch, and heat exchange generates hot air and hot water. To achieve the purpose of recovery of sensible heat from blast furnace slag, 1) First, the blast furnace slag discharged from the blast furnace 11 with a temperature of 1400-1500°C enters the sectioned bottom-blowing composite molten slag ditch 12, and at the same time, the compressed air of 1.5-2.0 MPa is injected at 8 The speed of ~10 m/s is blown from the bottom of the bottom-blown composite molten slag ditch, and the slag is stirred while ensuring the fluidity of the slag, so as to realize the radiant heat absorption of the thermal storage masonry on the top of the bottom-blown composite molten slag ditch. The heating body is heated to 1100-1250°C, and the air blown in from the bottom is also above 900°C at the outlet; 2) Secondly, the slag whose temperature has been lowered to 700-800°C enters the old slag treatment system through the connection unit. The slag is used for follow-up treatment; 3) When the blast furnace stops slag discharge, air is still blown into the bottom of the bottom-blown composite molten slag ditch, and the air is heated to 800-900°C during the process of passing through the regenerator; 4) Finally, the slag The cooling water (about 80°C) of the ditch passes through the heat exchanger 14 to replace the heat for production, and the hot air passes through the dust collector 16 and is used as the combustion-supporting air of the hot blast stove.

Claims (3)

1. A method for recovering the sensible heat of molten blast furnace slag, characterized in that the flow process is carried out in the following order: 1) Put the blast furnace slag with a temperature of 1400-1500°C into the sectioned bottom-blown composite molten slag ditch, and simultaneously Compressed air of 1.5-2.0 MPa is blown in from the bottom of the bottom-blown composite molten slag ditch at a speed of 8-10 m/s, stirring the slag while ensuring the fluidity of the molten slag, and realizing heat storage at the top of the bottom-blown composite molten slag ditch At this time, the regenerator is heated to 1100-1250°C; 2) The slag whose temperature has been lowered to 700-800°C enters the old slag treatment system through the connection unit for subsequent treatment of the slag; 3 ) means that when the blast furnace stops slag discharge, air is still blown into the bottom of the bottom-blown composite molten slag ditch, and the air is heated to 800-900°C in the process of passing through the regenerator; 4) After the hot air is dedusted, it is introduced into the waste heat power generation boiler For power generation, the cooling water of the slag ditch is used for production by displacing heat through a heat exchanger. 2. A method for recovering sensible heat from molten blast furnace slag according to claim 1, characterized in that, after the hot air is dedusted, it can also be used as combustion-supporting air of a hot blast stove. 3. The bottom-blowing composite molten slag ditch mentioned in the method of claim 1 is characterized in that it comprises a cement outer slag ditch, a ditch body support, a ditch body and a ditch cover, and the bottom of the cement outer slag ditch is provided with a ditch body support , the upper part of the ditch support is provided with a ditch body and ditch cover made of refractory materials, the inner surface of the ditch cover is provided with heat storage masonry, the slag flow channel is formed between the ditch body and the ditch cover, and the bottom of the ditch body is provided with Copper staves, cooling water pipes are installed inside the copper staves, bottom blowing air pipes are provided at the bottom of the copper staves, and blowing pipes are provided on the bottom blowing air pipes to communicate with the slag flow channel upwards.

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