Process for recycling waste gas heat energy of circular cooler

Abstract

The invention discloses an annular cooler waste gas heat energy recycling process which comprises an annular cooler, an induced draft fan is arranged on one side of the annular cooler, a dust remover is arranged on one side of the induced draft fan, a hot blast stove flue gas combustion fan is arranged on one side of the dust remover, and a hot blast stove flue gas preheater is arranged on one side of the hot blast stove flue gas combustion fan. The medium-temperature waste gas which is originally discarded at the second section of the circular cooler is used as combustion-supporting air of the hot-blast stove, so that the heat energy of the waste gas is recycled, the waste of a large amount of heat energy is avoided, the temperature of the preheated medium-temperature waste gas is increased, the arch crown temperature of the hot-blast stove is increased by 20 DEG C, the blast furnace air temperature is increased by 15 DEG C, and meanwhile, the coke ratio per ton of iron is saved by 1.2 kilograms; the consumption of coke can be reduced, and the energy cost of ironmaking is reduced; the dust content of medium-temperature waste gas entering the hot-blast stove reaches the standard through the efficient dust removal effect of the dust remover, it is guaranteed that the porosity of heat storage refractory materials in the hot-blast stove is not blocked, and the service life of the hot-blast stove is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of heat recovery of waste gas from annular coolers, and in particular to a process for recovering heat from waste gas from annular coolers. Background Art

[0002] In the steel production process, the ring cooler is one of the important equipment, and its operation process will produce a large amount of waste gas of different temperature ranges. Among them, the medium-temperature waste gas produced by the second stage of the ring cooler is usually greater than 200°C, containing considerable thermal energy. However, for a long time, due to the lack of effective recycling technology and equipment, most of this part of the medium-temperature waste gas has been directly discharged into the atmosphere, which not only caused a huge waste of energy, but also had a certain negative impact on the environment.

[0003] To this end, we have launched a process for recovering heat from waste gas from annular coolers. Summary of the invention

[0004] The purpose of the present invention is to provide a process for recovering heat energy from waste gas of an annular cooler to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above-mentioned object, the present invention provides the following technical scheme: a process for recycling heat energy of waste gas from an annular cooler, comprising: an annular cooler, an induced draft fan is arranged on one side of the annular cooler, a dust collector is arranged on one side of the induced draft fan, a hot blast stove combustion-supporting fan is arranged on one side of the dust collector, a hot blast stove combustion-supporting fan is arranged on one side of the hot blast stove combustion-supporting fan, a hot blast stove flue gas preheater is arranged on one side of the hot blast stove flue gas preheater, and a blast furnace is arranged on one side of the hot blast stove;

[0006] The above includes the following steps:

[0007] The medium-temperature exhaust gas with a temperature greater than 200°C from the second section of the ring cooler is led to the hot blast stove and blast furnace through the induced draft fan. Before entering the hot blast stove, the medium-temperature exhaust gas is first subjected to dust removal treatment by the dust collector. The medium-temperature exhaust gas after dust removal replaces the normal temperature air and enters the hot blast stove flue gas preheater for preheating. The preheated exhaust gas enters the hot blast stove as combustion-supporting air to participate in combustion.

[0008] Preferably, the medium-temperature exhaust gas replaces normal-temperature air as combustion-supporting air, and its temperature after passing through the hot blast furnace flue gas preheater is 60°C higher than that of normal-temperature air. After using this combustion-supporting air, the hot blast furnace dome temperature is increased by 20°C, the blast furnace air temperature is increased by 15°C, and 1.2 kg of coke is saved per ton of iron.

[0009] Preferably, the selection and parameter setting of the induced draft fan meet the requirement of stably conveying the medium-temperature exhaust gas from the second stage of the ring cooler to the hot blast stove and blast furnace, and the air volume and air pressure of the induced draft fan can adapt to the flow rate and conveying distance of the medium-temperature exhaust gas.

[0010] Preferably, the dust removal effect of the dust collector is less than 5 mg / L, so that the dust content of the medium-temperature exhaust gas entering the hot blast furnace meets the use standard of the hot blast furnace.

[0011] Preferably, the second section exhaust gas outlet of the ring cooler is connected to the inlet of the induced draft fan through a pipeline, the outlet of the induced draft fan is connected to the inlet of the dust collector, the outlet of the dust collector is connected to the inlet of the hot blast stove combustion-supporting fan, the outlet of the hot blast stove combustion-supporting fan is connected to the inlet of the hot blast flue gas preheater, the outlet of the hot blast stove flue gas preheater is connected to the inlet of the hot blast stove, and the hot blast stove is connected to the blast furnace.

[0012] Preferably, it also includes an automated control system, which is used to monitor parameters such as the temperature and flow rate of the exhaust gas from the annular cooler, the dome temperature of the hot blast furnace, the blast furnace air temperature and the coke ratio, and automatically adjust the speed of the induced draft fan, the cleaning frequency of the dust collector and the combustion parameters of the hot blast furnace according to the monitoring data.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] (1) The medium-temperature exhaust gas that was originally discarded in the second stage of the ring cooler is used as the combustion-supporting air of the hot blast furnace, realizing the recovery and reuse of the exhaust gas heat energy, avoiding the waste of a large amount of heat energy. The temperature of the preheated medium-temperature exhaust gas is increased, so that the dome temperature of the hot blast furnace is increased by 20°C and the blast furnace air temperature is increased by 15°C. The increase in the blast furnace air temperature can significantly improve the heat exchange conditions in the blast furnace ironmaking process and promote more efficient reactions in the furnace. At the same time, the coke ratio is saved by 1.2 kg per ton of iron, which means that when producing the same amount of iron, the consumption of coke can be reduced, reducing the energy cost of ironmaking. Based on the annual iron production of 860 million tons in my country, the country can save 1.03 million tons of coke and save 2.06 billion yuan in costs, bringing huge economic benefits to steel companies and meeting the national policy requirements for energy conservation and emission reduction;

[0015] (2) The efficient dust removal function of the dust collector ensures that the dust content of the medium-temperature exhaust gas entering the hot blast furnace meets the standard, ensures that the porosity of the heat storage refractory material inside the hot blast furnace is not blocked, and ensures the service life of the hot blast furnace.

[0016] (3) By increasing the temperature of the hot blast stove dome and the blast furnace air temperature, more favorable thermal conditions are created for blast furnace ironmaking. At higher air temperatures, the reduction reaction in the furnace is more complete, the quality of molten iron is improved, the impurity content of pig iron is reduced, and the product quality is better. This helps steel companies produce higher quality steel, enhance their market competitiveness, and meet the market demand for high-end steel products. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall process of the present invention.

[0018] In the figure: 1. Annular cooler; 2. Induced draft fan; 3. Dust collector; 4. Hot blast stove flue gas preheater; 5. Hot blast stove combustion-supporting fan; 6. Hot blast stove; 7. Blast furnace. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] See also Figure 1 The present invention provides a technical solution: a process for recycling heat energy of waste gas from an annular cooler, comprising: an annular cooler 1, an induced draft fan 2 is arranged on one side of the annular cooler 1, a dust collector 3 is arranged on one side of the induced draft fan 2, a hot blast stove combustion-supporting fan 5 is arranged on one side of the dust collector 3, a hot blast stove combustion-supporting fan 5 is arranged on one side of the hot blast stove combustion-supporting fan 5, a hot blast stove flue gas preheater 4 is arranged on one side of the hot blast stove flue gas preheater 4, a hot blast stove 6 is arranged on one side of the hot blast stove 6, and a blast furnace 7 is arranged on one side of the hot blast stove 6;

[0021] Annular cooler 1: As the source of waste gas, its second-stage waste gas outlet is closely connected to the inlet of induced draft fan 2 through a dedicated pipeline. The Annular cooler 1 can use a large-scale sintering annular cooler commonly seen on the market;

[0022] Induced draft fan 2: installed on one side of the ring cooler 1, its function is to draw out the medium-temperature exhaust gas generated by the second stage of the ring cooler 1 and transport it to the subsequent equipment. The induced draft fan 2 can use a centrifugal induced draft fan, which has the characteristics of high efficiency and energy saving, and a large adjustment range of air volume and air pressure. Its air volume and air pressure can be flexibly adjusted according to the flow rate and transportation distance of the medium-temperature exhaust gas to ensure that the exhaust gas is stably transported to the hot blast furnace 6 and the blast furnace 7. The outlet of the induced draft fan 2 is connected to the inlet of the dust collector 3 through a pipeline;

[0023] Dust collector 3: It is arranged on one side of the induced draft fan 2 and is used to remove dust from the medium-temperature exhaust gas. The dust collector 3 can adopt a pulse bag dust collector, and its dust removal effect is less than 5mg / L, which can effectively remove dust particles in the exhaust gas, so that the dust content of the medium-temperature exhaust gas entering the hot blast furnace 6 meets the use standard of the hot blast furnace. The outlet of the dust collector 3 is connected to the inlet of the hot blast furnace combustion-supporting fan 5;

[0024] Hot blast furnace combustion-supporting fan 5: located on one side of the dust collector 3, an axial flow fan is selected to provide sufficient pressure for the preheated exhaust gas so that it can smoothly enter the hot blast furnace 6 to participate in combustion. The outlet of the hot blast furnace combustion-supporting fan 5 is connected to the inlet of the hot blast furnace flue gas preheater 4;

[0025] Hot blast furnace flue gas preheater 4: arranged on one side of the hot blast furnace combustion-supporting fan 5, a finned tube preheater is adopted, which has the advantages of high heat transfer efficiency and compact structure, and its function is to further preheat the medium-temperature exhaust gas after dust removal, and to increase the temperature of the exhaust gas. The outlet of the hot blast furnace flue gas preheater 4 is connected to the combustion-supporting air inlet of the hot blast furnace 6;

[0026] Hot blast furnace 6: As one of the core equipment for heat energy utilization, an internal combustion hot blast furnace can be selected, which has a reasonable structure and high combustion efficiency. One side of the hot blast furnace 6 is connected to the blast furnace 7 to provide high-temperature hot blast for the blast furnace 7;

[0027] Blast furnace 7: It is a key equipment for steel production, receiving high-temperature hot air from hot blast furnace 6 for smelting iron ore;

[0028] The above includes the following steps:

[0029] The medium-temperature exhaust gas with a temperature greater than 200°C from the second section of the ring cooler 1 is introduced into the hot blast furnace 6 and the blast furnace 7 through the induced draft fan 2. Before entering the hot blast furnace 6, the medium-temperature exhaust gas is first subjected to dust removal treatment by the dust collector 3. The medium-temperature exhaust gas after dust removal replaces the normal temperature air and enters the hot blast furnace flue gas preheater 4 for preheating. The preheated exhaust gas enters the hot blast furnace 6 as combustion-supporting air to participate in combustion.

[0030] The medium-temperature exhaust gas replaces normal-temperature air as combustion-supporting air, and its temperature after passing through the hot-blast furnace flue gas preheater 4 is 60°C higher than that of normal-temperature air. After using the combustion-supporting air, the dome temperature of the hot-blast furnace 6 is increased by 20°C, and the air temperature of the blast furnace 7 is increased by 15°C, saving 1.2 kg of coke per ton of iron.

[0031] The selection and parameter setting of the induced draft fan 2 meet the requirement of stably conveying the medium-temperature exhaust gas from the second stage of the ring cooler to the hot blast stove 6 and the blast furnace 7. The air volume and air pressure of the induced draft fan 2 can adapt to the flow rate and conveying distance of the medium-temperature exhaust gas.

[0032] The dust removal effect of the dust collector 3 is less than 5 mg / L, so that the dust content of the medium-temperature exhaust gas entering the hot blast furnace 6 meets the use standard of the hot blast furnace.

[0033] The second section exhaust gas outlet of the annular cooler 1 is connected to the inlet of the induced draft fan 2 through a pipeline, the outlet of the induced draft fan 2 is connected to the inlet of the dust collector 3, the outlet of the dust collector 3 is connected to the inlet of the hot blast stove combustion-supporting fan 5, the outlet of the hot blast stove combustion-supporting fan 5 is connected to the inlet of the hot blast stove flue gas preheater 4, the outlet of the hot blast stove flue gas preheater 4 is connected to the inlet of the hot blast stove 6, and the hot blast stove 6 is connected to the blast furnace 7.

[0034] It also includes an automatic control system, which is used to monitor the exhaust gas temperature and flow rate of the ring cooler 1, the dome temperature of the hot blast furnace 6, the wind temperature of the blast furnace 7, the coke ratio and other parameters, and automatically adjust the speed of the induced draft fan 2, the cleaning frequency of the dust collector 3 and the combustion parameters of the hot blast furnace 6 according to the monitoring data.

[0035] Specifically, when in use, during the steel production process, the annular cooler 1 cools the sintered ore, and the second stage thereof generates medium-temperature exhaust gas with a temperature greater than 200°C. The induced draft fan 2 generates sufficient suction force by virtue of its specific selection and parameter settings, overcomes the pipeline resistance and the pressure required for exhaust gas transportation, and stably draws this part of the medium-temperature exhaust gas out of the annular cooler 1. The air volume and air pressure of the induced draft fan 2 are precisely matched according to the flow rate of the medium-temperature exhaust gas and the distance to the hot blast stove 6 and the blast furnace 7, ensuring that the exhaust gas can be continuously and stably transported;

[0036] The introduced medium-temperature exhaust gas contains a certain amount of impurities such as dust. If it directly enters the hot blast furnace 6, it will cause wear and tear on the equipment and affect the combustion effect. Therefore, the exhaust gas is introduced into the dust collector 3. The dust collector 3 adopts a high-efficiency dust removal technology, and its dust removal efficiency is not less than 95%. It can effectively remove most of the dust in the exhaust gas, so that the dust content of the medium-temperature exhaust gas entering the hot blast furnace 6 meets the strict use standards of the hot blast furnace 6, ensuring the stable operation and combustion quality of the hot blast furnace 6.

[0037] The medium-temperature exhaust gas after dust removal enters the hot blast furnace combustion-supporting fan 5. The hot blast furnace combustion-supporting fan 5 cooperates with the hot blast furnace flue gas preheater 4 to allow the hot blast furnace flue gas preheater 4 to preheat the medium-temperature exhaust gas using the waste heat of the flue gas discharged after the hot blast furnace 6 is burned. In this heat exchange process, the medium-temperature exhaust gas absorbs the heat of the flue gas and the temperature is further increased. Compared with the air at normal temperature, the temperature of the preheated medium-temperature exhaust gas can be increased by 60°C, which provides higher heat energy for subsequent combustion as combustion-supporting air;

[0038] The hot blast furnace flue gas preheater 4 delivers gas to the hot blast furnace 6. In the hot blast furnace 6, the medium-temperature exhaust gas participates in the combustion process as combustion-supporting air. Due to its high temperature, it can provide more sufficient heat for combustion, promote more complete combustion of fuel, and thus improve the combustion efficiency of the hot blast furnace 6. The high-temperature hot air generated by the combustion is delivered to the blast furnace 7 to provide heat for ironmaking in the blast furnace 7.

[0039] The automated control system monitors key parameters such as the temperature and flow of the exhaust gas from the annular cooler 1, the dome temperature of the hot blast furnace 6, the wind temperature of the blast furnace 7, and the coke ratio in real time. When the temperature and flow of the exhaust gas from the annular cooler 1 change, the system automatically adjusts the rotation speed of the induced draft fan 2 according to the preset logic to ensure stable transportation of the medium-temperature exhaust gas; when the resistance change of the dust collector 3 is monitored and it is determined that cleaning is required, the cleaning frequency of the dust collector 3 is automatically adjusted to maintain the efficient dust removal performance of the dust collector 3; at the same time, according to the changes in the dome temperature of the hot blast furnace 6, the wind temperature of the blast furnace 7, and the coke ratio, the combustion parameters of the hot blast furnace 6 are automatically adjusted to ensure the stable operation of the hot blast furnace 6 and maintain the efficient ironmaking state of the blast furnace 7.

[0040] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A process for recycling heat energy from waste gas of an annular cooler, characterized in that: include: A ring cooler (1), wherein an induced draft fan (2) is arranged on one side of the ring cooler (1), a dust collector (3) is arranged on one side of the induced draft fan (2), a hot blast furnace combustion-supporting fan (5) is arranged on one side of the dust collector (3), a hot blast furnace combustion-supporting fan (4) is arranged on one side of the hot blast furnace combustion-supporting fan (5), a hot blast furnace flue gas preheater (4) is arranged on one side of the hot blast furnace flue gas preheater (4), and a blast furnace (7) is arranged on one side of the hot blast furnace (6); The above includes the following steps: The medium-temperature exhaust gas with a temperature greater than 200° C. from the second stage of the ring cooler (1) is introduced into the hot blast furnace (6) and the blast furnace (7) through the induced draft fan (2). Before entering the hot blast furnace (6), the medium-temperature exhaust gas is first subjected to dust removal treatment in the dust collector (3). The medium-temperature exhaust gas after dust removal replaces the normal temperature air and enters the hot blast furnace flue gas preheater (4) for preheating. The preheated exhaust gas enters the hot blast furnace (6) as combustion-supporting air to participate in combustion.

2. A process for recycling heat energy from waste gas from an annular cooler according to claim 1, characterized in that: The selection and parameter setting of the induced draft fan (2) meet the requirements for stably conveying the medium-temperature exhaust gas from the second stage of the ring cooler to the hot blast stove (6) and the blast furnace (7), and the air volume and air pressure of the induced draft fan (2) can adapt to the flow rate and conveying distance of the medium-temperature exhaust gas.

3. The process for recycling heat energy from waste gas from an annular cooler according to claim 1, characterized in that: The dust removal effect of the dust collector (3) is such that the dust content is less than 5 mg / L, so that the dust content of the medium-temperature exhaust gas entering the hot blast furnace (6) meets the use standard of the hot blast furnace.

4. The process for recycling heat energy from waste gas from an annular cooler according to claim 1, characterized in that: The second section exhaust gas outlet of the annular cooler (1) is connected to the inlet of the induced draft fan (2) through a pipeline, the outlet of the induced draft fan (2) is connected to the inlet of the dust collector (3), the outlet of the dust collector (3) is connected to the combustion air inlet of the hot blast furnace combustion-supporting fan (5), the outlet of the hot blast furnace combustion-supporting fan (5) is connected to the inlet of the hot blast furnace flue gas preheater (4), the outlet of the hot blast furnace flue gas preheater (4) is connected to the inlet of the hot blast furnace (6), and the hot blast furnace (6) is connected to the blast furnace (7).

5. The process for recycling heat energy from waste gas of an annular cooler according to claim 1, characterized in that: It also includes an automatic control system, which is used to monitor the exhaust gas temperature and flow rate of the ring cooler (1), the dome temperature of the hot blast furnace (6), the wind temperature of the blast furnace (7) and the coke ratio parameters, and automatically adjust the rotation speed of the induced draft fan (2), the cleaning frequency of the dust collector (3) and the combustion parameters of the hot blast furnace (6) according to the monitoring data.

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