Blast furnace hot blast stove waste heat and water granulated slag drying combined utilization device and method

Abstract

The invention relates to a blast furnace hot blast stove waste heat and water granulated slag drying combined utilization device and method. The device mainly comprises a fixed bed dry desulphurization device, an air mixing chamber, a vertical roller grinding device, a dust removal component and a combustion furnace. Gas shunted from the hot-blast stove waste heat system is subjected to dry desulfurization treatment through the fixed bed dry desulfurization device and then is discharged into the water granulated slag drying system, and the water granulated slag drying system is transformed, so that the total amount of water introduced by spraying in the hot-blast stove waste heat system is reduced; and moreover, the water granulated slag is dried by using the temperature of the hot flue gas, so that the combustion amount of blast furnace gas is reduced or basically replaced, the water granulated slag and the blast furnace gas are combined, coordinated and utilized, the energy waste is reduced, the gas consumption is reduced, and harm is turned into benefit.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial solid waste and waste heat recycling, and specifically relates to a device and method for combined utilization of blast furnace hot blast stove waste heat and slag drying. Background Art

[0002] In the existing environmental protection system of the blast furnace hot blast stove, a combined desulfurization and denitrification unit needs to be added to achieve the goal of ultra-low emissions of tail gas pollutants. The current process generally follows the technical route of "denitrification → water medium rapid cooling → desulfurization". There are significant process bottlenecks in the implementation process: since by-products and unreacted desulfurizers will be produced after desulfurization and enter the subsequent process, they need to be captured by bag filters and then recycled, but bag filters cannot withstand high temperatures; therefore, the high-temperature flue gas (about 280°C) after selective catalytic reduction (SCR denitrification) treatment needs to be cooled by a spray cooling process to reduce the temperature to the critical point of 180°C (actual operation requires ≤170°C) before the subsequent desulfurization tower operation can be carried out. However, this technical process has the following defects: 1. The use of direct water spraying results in two resource wastes, of which the evaporation water consumption reaches 3.5-4.2m 3 / 10,000 cubic meters of flue gas (calculated according to GB4053-2019 standard), and the sensible heat in the temperature zone of 280℃→170℃ (about 210kJ / kg) is not recovered, which is equivalent to a loss of 12-15% of the fuel combustion heat energy; 2. Equipment reliability risk. Direct water spraying will cause the dew point corrosion rate of the spray section flue to reach 0.15-0.25mm / year (refer to NB / T47056 standard), thereby increasing the frequency of periodic shutdown maintenance by 30%, affecting the continuity of the operation of the entire blast furnace system; thus, this process defect will cause the environmental protection cost per ton of iron to increase by about 8-12 yuan (refer to the energy consumption index of the Chinese Society for Metals), and there is a gap with the waste heat recovery and utilization requirements in GB21256-2020 "Energy-Saving Design Code for Iron and Steel Enterprises". It is urgent to develop a new type of cascade waste heat utilization and dry cooling integrated technology. The existing fixed bed dry desulfurization equipment is generally suitable for medium and small gas boilers, heating furnaces and other medium and low sulfur concentration (≤200mg / m 3 ) Flue gas treatment with small flue gas volumes is basically unusable in the field of blast furnace hot blast stoves.

[0003] Meanwhile, blast furnace slag, a by-product of the metallurgical industry, is a porous solid waste formed during the iron ore smelting process (blast furnace) after high-temperature melting and rapid water cooling. Due to the nature of the process, this material has a moisture content exceeding 10%, requiring dehydration and drying pretreatment before it can be utilized as a building material. Current industrial applications are primarily focused on cement admixtures, high-performance concrete admixtures, and the preparation of ultrafine mineral powders. In the existing drying process system, when using a vertical roller mill system for hot air drying, the heat exchange efficiency is significantly reduced due to the excessively high humidity saturation (>60% RH) of the circulating flue gas. Specifically, the thermal energy utilization rate is reduced to 65%-75% of the design value; the gas consumption index exceeds the industry benchmark by 20-30%; and the energy consumption per unit product drying increases to 2.8GJ / t. To address these technical issues, existing technologies generally employ the following improvements: 1. Constructing a multi-stage waste heat recovery system (including a flue gas latent heat recovery device); 2. Developing an intelligent humidity control module (integrating dew point monitoring and dynamic air distribution technology); and 3. Optimizing the combustion chamber air-fuel ratio control algorithm (achieving ±1% gas calorific value adaptation). However, these process methods all require significant modifications to existing equipment, significantly increasing costs.

[0004] In view of the defects of the above two processes, if the technical problems of the above two processes can be solved with as little equipment modification as possible, the overall production cost and environmental cost of steel enterprises will be greatly reduced.

[0005] There are also technical solutions in the prior art that couple the two processes. Chinese invention patent publication CN117125914A discloses a blast furnace slag micropowder preparation and hot blast furnace flue gas purification treatment system. The blast furnace gas heated by the hot blast furnace is directly introduced into the water slag drying system for direct drying, rather than using combustion, thereby combining the hot blast system and the water slag system. However, since the temperature of the blast furnace gas discharged from the hot blast furnace is lower than that of the original combustion gas, in order to achieve the same drying effect, it is necessary to increase the drying time or increase the air volume. In addition, since the blast furnace gas heated by the hot blast furnace is directly introduced, the gas contains a large amount of nitrogen and sulfur compounds, which will affect the quality of the water slag during the drying process and increase the difficulty of the desulfurization and denitrification process of the generated gas. Summary of the Invention

[0006] In response to the above technical problems, the present invention proposes a method of improving and optimizing the existing hot blast furnace denitrification and desulfurization process, subjecting a portion of the flue gas after denitrification to fixed-bed dry desulfurization, and using the high-temperature flue gas after denitrification and desulfurization to replace the existing hot air for drying slag formed by burning blast furnace gas, thereby greatly reducing the consumption of slag drying gas. At the same time, it also reduces the flue gas entering the existing process desulfurization, thereby reducing the spraying amount of water medium, and reducing the frequency of heat loss, pipeline corrosion and other problems. On the premise of solving the above technical problems, the existing process and equipment are modified as little as possible, and the waste heat of the blast furnace hot blast furnace is combined with the drying of slag, so as to fully develop and utilize the waste heat resources, reduce the use of gas, achieve energy conservation and carbon reduction, save costs, and turn harm into benefit.

[0007] This is achieved through the following technical means:

[0008] A device for combined utilization of blast furnace hot blast stove waste heat and slag drying comprises a fixed bed dry desulfurization device, an air mixing chamber, a vertical roller mill device, a dust removal component and a combustion furnace.

[0009] The combustion furnace is used to burn blast furnace gas and then discharge high-temperature gas.

[0010] The inlet end of the fixed bed dry desulfurization device is connected to the outlet end of the hot blast furnace denitrification device, and the connection position is located at the front end of the water spray cooling device.

[0011] The air mixing chamber is used to discharge the high-temperature gas after internal mixing (the mixing here is mainly to choose between desulfurization high-temperature gas or to introduce high-temperature combustion gas when the desulfurization high-temperature gas flow is insufficient or fails), including a first hot air inlet, a second hot air inlet and a mixed air outlet; the first hot air inlet is connected to the outlet end of the fixed bed desulfurization device, and the second hot air inlet is connected to the combustion gas outlet of the combustion furnace.

[0012] The vertical roller mill device is used to crush, grind and dry the water slag. The vertical roller mill device is provided with a water slag inlet, a high-temperature gas inlet and a low-temperature gas discharge port. The water slag inlet is used to discharge the raw water slag, and the high-temperature gas inlet is only connected to the mixed air outlet of the mixed air chamber.

[0013] The dust removal component is used for performing dust removal operation on the gas discharged from the low-temperature gas discharge port of the vertical roller mill device.

[0014] Preferably, the fixed-bed dry desulfurization device is a radial fixed-bed desulfurization tower, comprising a tower body, an air inlet chamber, an air collecting chamber, a fixed bed layer and a supporting structure; the tower body is a multi-layer concentric cylindrical structure, an air inlet chamber is provided on the outside of the tower body, an air collecting chamber is provided in the center of the tower body, and an annular fixed bed layer is provided between the air inlet chamber and the air collecting chamber; the fixed bed layer is filled with granular desulfurizer, and a grid or a porous plate is provided at the bottom of the fixed bed layer as a supporting structure to support the desulfurizer particles.

[0015] Preferably, the combined utilization device of blast furnace hot blast stove waste heat and slag drying also includes one or more combustion-supporting fans; the combustion furnace includes a combustion-supporting gas inlet, a blast furnace gas inlet and a combustion gas outlet, the combustion-supporting gas inlet is connected to the combustion-supporting fan, the blast furnace gas inlet is connected to the exhaust outlet of the blast furnace gas network, and the combustion gas exhaust outlet discharges the high-temperature gas after combustion.

[0016] Preferably, the device for combined utilization of waste heat from the blast furnace hot blast stove and slag drying also includes a denitrification device, a spraying device, a desulfurization tower and a desulfurization dust collector; the denitrification device is used to denitrify the flue gas discharged from the hot blast stove; the spraying device is used to spray the high-temperature flue gas after the denitrification treatment with a water medium for cooling; a three-way valve is provided on the pipeline after the denitrification device and before the spraying device, the inlet of the three-way valve is connected to the outlet of the denitrification device, the first outlet of the three-way valve is connected to the inlet end of the fixed bed dry desulfurization device, and the second outlet of the three-way valve is connected to the inlet end of the spraying device.

[0017] Preferably, the desulfurization dust collector is used to remove dust from the flue gas after desulfurization.

[0018] Preferably, the desulfurization tower is a dense phase coherent tower semi-dry desulfurization tower; and the desulfurization dust collector is a bag dust collector.

[0019] Preferably, the dust removal components include a bag dust collector, a slag micropowder finished product bin, a vertical mill induced draft fan and a vertical mill chimney; the inlet of the bag dust collector is connected to the low-temperature gas discharge port of the vertical roller mill device, the particle outlet of the bag dust collector is connected to the inlet of the slag micropowder finished product bin, the gas outlet of the bag dust collector is connected to the inlet of the vertical mill induced draft fan, the outlet of the vertical mill induced draft fan is connected to the vertical mill chimney, and the outlet of the vertical mill induced draft fan is not connected to any gas inlet of the vertical roller mill device.

[0020] Preferably, the denitrification device is an SCR denitrification device.

[0021] A method for combining waste heat from a blast furnace hot blast stove with slag drying comprises the following steps:

[0022] (1) The high-temperature flue gas coming out of the hot blast furnace and after being denitrified by the denitrification device is diverted through a three-way valve to obtain a first high-temperature flue gas and a second high-temperature flue gas. The first high-temperature flue gas is discharged into a fixed-bed dry desulfurization device for dry desulfurization, and the second high-temperature flue gas is discharged into a spraying device for spraying with a water medium and then discharged into a desulfurization tower for desulfurization. The gas obtained after desulfurization is then discharged into a desulfurization dust collector for dust removal and then discharged through a desulfurization induced draft fan.

[0023] (2) The desulfurized high-temperature gas obtained after dry desulfurization in step (1) is introduced into the air mixing chamber. When the flow rate of the desulfurized high-temperature gas is insufficient or fails, the blast furnace gas discharged from the blast furnace gas network and the combustion-supporting air discharged from the combustion-supporting blower are discharged into the combustion furnace together for combustion, and the high-temperature combustion gas obtained after the combustion is introduced into the air mixing chamber; wherein the volume flow rate of the desulfurized high-temperature gas introduced into the air mixing chamber is a ratio of the volume flow rate of the high-temperature combustion gas introduced into the air mixing chamber to the volume flow rate of the high-temperature combustion gas introduced into the air mixing chamber (2.3 to 3.5):1.

[0024] (3) The raw material water slag is discharged into a vertical roller mill device for crushing and grinding. At the same time, the desulfurized high-temperature gas or high-temperature combustion gas in the air mixing chamber of step (2) is discharged into the vertical roller mill device to dry the water slag in the crushing and grinding process to obtain a solid-gas mixture.

[0025] (4) The solid-gas mixture is discharged into a bag filter for solid-gas separation, and the dust separation obtains solid dust particles and dust removal gas.

[0026] (5) The obtained solid dust particles are discharged into the slag micropowder finished product bin to obtain slag micropowder products; the dust removal gas is discharged into the vertical mill chimney through the vertical mill induced draft fan for subsequent treatment.

[0027] Preferably, the method for combined utilization of waste heat from a blast furnace hot blast stove and slag drying is carried out using the above-mentioned device for combined utilization of waste heat from a blast furnace hot blast stove and slag drying.

[0028] Preferably, the temperature of the high-temperature flue gas after denitration treatment in the denitration device after coming out of the hot blast furnace in step (1) is 256-298°C; the temperature of the flue gas discharged into the dense phase coherent tower semi-dry desulfurization tower is 166-178°C.

[0029] Preferably, the ratio of the volume flow rates of the first high-temperature flue gas and the second high-temperature flue gas in step (1) is (1-3):(7-9). This is because the amount of high-temperature flue gas required for the slag in a blast furnace ironmaking plant of the same level is about 10-30% of the total amount of flue gas generated by the hot blast furnace of the plant. Therefore, through calculation and the actual situation of the ironmaking plant, the volume ratio of the two is set to this volume ratio, so that the heat can be more fully utilized without causing excessive modifications to the original desulfurization and denitrification equipment.

[0030] Preferably, in step (2), when the flow rate of the desulfurized high-temperature gas is insufficient, the blast furnace gas discharged from the blast furnace gas network and the combustion-supporting air discharged from the combustion-supporting fan can be discharged into the combustion furnace together for combustion, and the high-temperature combustion gas obtained after combustion is introduced into the air mixing chamber to be mixed with the desulfurized high-temperature gas (the mixing ratio can be any mixing ratio, which depends on the degree of insufficient flow rate of the desulfurized high-temperature gas. The overall configuration is set according to the ratio of the volume flow rate of the desulfurized high-temperature gas to the volume flow rate of the high-temperature combustion gas introduced into the air mixing chamber of (2.3 to 3.5):1). That is, in one embodiment, in step (2), the gas discharged from the air mixing chamber is a mixture of the desulfurized high-temperature gas and the high-temperature combustion gas.

[0031] As a preference, the ratio between the amount of raw material water slag added and the amount of mixed hot air added in step (3) is (95-106 tons): (153000-225000Nm 3 / h).

[0032] Preferably, the moisture content of the raw material slag in step (3) is 9-13 wt.%, and the moisture content of the slag powder product obtained in step (5) is 0.06-0.15 wt.%.

[0033] Preferably, the raw material slag in step (3) is blast furnace water-quenched slag formed by water-quenching the molten waste slag produced during the blast furnace ironmaking process.

[0034] The technical effects of the present invention are:

[0035] (1) In the prior art, the blast furnace gas after hot blast furnace treatment adopts the process flow of denitrification → water medium rapid cooling → desulfurization. However, since the fixed bed dry desulfurization occupies a large area and produces a large amount of solid waste, and the fixed bed dry desulfurization device is only suitable for treating small gas volumes and low sulfur content gases, it is not suitable as the main desulfurization device for hot blast furnace flue gas. However, the present invention newly sets up a radial fixed-bed desulfurization tower as a fixed-bed dry desulfurization device to dry-desulfurize a portion of the flue gas after denitrification and then contact it with slag. The overall device modification amount is relatively small. After the gas after fixed-bed dry desulfurization is efficiently contacted with slag, the calcium oxide in the slag will further remove the residual sulfur in the gas, so that not only the high-temperature gas realizes the drying operation of the slag, but also the fixed-bed dry desulfurization is effectively supplemented. That is, the present invention fully utilizes the waste heat of the high-temperature flue gas after denitrification, and removes sulfur on the basis of efficient denitrification by passing the denitrified flue gas through fixed-bed dry desulfurization without substantially reducing the flue gas temperature. Then, the flue gas after denitrification and removal of inorganic sulfur is used as hot flue gas for slag grinding and drying, and then the sulfur in the flue gas is further effectively removed. Moreover, since it is a high-temperature gas generated after denitrification and dry desulfurization, its gas toxicity is also relatively low, so that the present invention introduces a coordinated effect of fixed-bed dry desulfurization and slag drying, which not only dries the slag more efficiently but also efficiently treats the waste gas.

[0036] (2) The present invention uses the fixed-bed dry desulfurization device specifically configured by the present invention to perform dry desulfurization on the high-temperature flue gas after denitrification. Since the flue gas discharged from the fixed-bed dry desulfurization device is high-temperature flue gas, this part of the flue gas is equivalent to the residual sulfur in it reacting with the calcium oxide in the water slag under high-temperature conditions while drying the water slag. As is well known, the calcium in the slag in the form of calcium oxide will have an adverse effect on the subsequent effective utilization of the slag. Generally, it needs to be treated to form calcium salts or couplings. The present invention, through the specific configuration of the fixed-bed dry desulfurization device, enables this part of the high-temperature flue gas to react with calcium oxide more efficiently to generate couplings, further improving the subsequent utilization of the water slag and reducing the difficulty and cost of subsequent water slag processing. Therefore, such a configuration circumvents some of the disadvantages of the fixed-bed dry desulfurization device (it can only process small amounts of gas with low sulfur content) and optimizes the advantages of the device (the discharged gas is high-temperature flue gas).

[0037] (3) The present invention retains the combustion furnace process. When the flue gas volume discharged by the newly installed fixed-bed dry desulfurization device is insufficient or a fault or maintenance occurs, the combustion furnace can be activated to continuously dry the water slag. Such a modification has a relatively low modification workload for the overall process. The fixed-bed dry desulfurization device can basically replace the blast furnace gas combustion gas of the combustion furnace in normal process. In abnormal process, the combustion furnace can realize standby supplement for the fixed-bed dry desulfurization device, thereby not adversely affecting the water slag treatment process. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic diagram of the layout of a device for combined utilization of blast furnace hot blast stove waste heat and slag drying according to an embodiment of the present invention.

[0039] In the figure: 101 - denitrification device; 102 - 1st three-way valve; 103 - spray device; 104 - desulfurization tower, 105 - desulfurization dust collector; 106 - desulfurization induced draft fan; 107 - 2nd three-way valve; 108 - 3rd three-way valve; 109 - hot blast furnace chimney; 200 - fixed-bed dry desulfurization device; 201 - blast furnace gas network; 202 - 1st combustion-supporting fan; 203 - 2nd combustion-supporting fan; 204 - combustion furnace; 205 - air mixing chamber; 206 - raw material water slag; 207 - vertical roller mill; 208 - bag dust collector; 209 - slag powder finished product warehouse; 210 - vertical mill induced draft fan; 211 - vertical mill chimney

[0040] The arrows in the diagram indicate the direction of flow of material, gas or energy. DETAILED DESCRIPTION

[0041] The process technology scheme of the present invention is further illustrated below by combining embodiments and drawings. The orientations involved in this specification are based on the orientations of the present invention during normal operation, and do not limit the orientations during storage and transportation. They only represent relative positional relationships, not absolute positional relationships. Specific implementation methods Unless otherwise specified, each feature is only an example of a series of equivalent or similar features. It is only to help understand the present invention, and those skilled in the art should understand that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0042] Example 1

[0043] This embodiment is used to illustrate a device for combining the utilization of waste heat from a blast furnace hot blast stove and slag drying. It is a technical solution for the overall transformation of the existing hot blast stove flue gas denitrification and desulfurization process equipment and slag treatment process equipment in a blast furnace ironmaking plant. Figure 1 The diagram includes a fixed-bed dry desulfurization device, an air mixing chamber, a vertical roller mill, dust removal components, a combustion furnace, a denitrification device, a spray device, a desulfurization tower and a desulfurization dust collector.

[0044] The combustion furnace is used to burn blast furnace gas and then discharge high-temperature gas.

[0045] The inlet end of the fixed bed dry desulfurization device is connected to the outlet end of the hot blast furnace denitrification device, and the connection position is located at the front end of the water spray cooling device.

[0046] The fixed-bed dry desulfurization device is a radial fixed-bed desulfurization tower, comprising a tower body, an air inlet chamber, an air collecting chamber, a fixed bed layer and a supporting structure; the tower body is a multi-layer concentric cylindrical structure, with an air inlet chamber provided on the outside of the tower body, an air collecting chamber provided in the center of the tower body, and an annular fixed bed layer provided between the air inlet chamber and the air collecting chamber; the fixed bed layer is filled with granular desulfurizer, and a grid or a porous plate is provided at the bottom of the fixed bed layer as a supporting structure to support the desulfurizer particles.

[0047] The air mixing chamber is used to discharge the high-temperature gas after internal mixing, and includes a first hot air inlet, a second hot air inlet and a mixed air outlet; the first hot air inlet is connected to the combustion gas outlet of the combustion furnace, and the second hot air inlet is connected to the outlet end of the fixed bed desulfurization device.

[0048] The vertical roller mill device is used to crush, grind and dry the water slag. The vertical roller mill device is provided with a water slag inlet, a high-temperature gas inlet and a low-temperature gas discharge port. The water slag inlet is used to discharge the raw water slag, and the high-temperature gas inlet is only connected to the mixed air outlet of the mixed air chamber.

[0049] The dust removal component is used for performing dust removal operation on the gas discharged from the low-temperature gas discharge port of the vertical roller mill device.

[0050] like Figure 1 As shown, the device includes two combustion-supporting fans (the first combustion-supporting fan and the second combustion-supporting fan, one for backup and the other for use); the combustion furnace includes a combustion-supporting gas inlet, a blast furnace gas inlet, and a combustion gas outlet. The combustion-supporting gas inlet is connected to the combustion-supporting fan, the blast furnace gas inlet is connected to the exhaust outlet of the blast furnace gas network, and the combustion gas outlet discharges the high-temperature gas after combustion. The high-temperature combustion gas after combustion is the drying gas from the water slag drying in the original process. The temperature of the high-temperature combustion gas is about 900°C. It is cooled to 300°C as drying gas by the secondary air reflux of the original system. The flue gas volume required for drying is about 60,000-70,000 Nm 3 / h. In this embodiment, the device is retained as a whole and serves as backup drying gas when the desulfurization high-temperature gas flow is insufficient or fails or is under maintenance, so as not to cause interruption of the water slag process.

[0051] The denitrification device is used to denitrify the flue gas discharged from the hot blast furnace; the spraying device is used to spray the high-temperature flue gas of the main body after the denitrification treatment with a water medium for cooling; a first three-way valve is provided on the pipeline after the denitrification device and before the spraying device, the inlet of the first three-way valve is connected to the outlet of the denitrification device, the first outlet of the first three-way valve is connected to the inlet end of the fixed bed dry desulfurization device, and the second outlet of the first three-way valve is connected to the inlet end of the spraying device; the desulfurization tower described in this embodiment is a dense phase coherent tower semi-dry desulfurization tower.

[0052] The desulfurization dust collector (the desulfurization dust collector in this embodiment is a bag dust collector) is used to remove dust from the flue gas after desulfurization. Figure 1 As shown, the gas after dust removal by the desulfurization dust collector is discharged into the second three-way valve through the desulfurization induced draft fan. The second three-way valve returns part of the gas to the front end of the desulfurization tower (received through the third three-way valve), and the other part of the gas is discharged through the hot blast furnace chimney. This operation is mainly to control the flue gas flow rate in the desulfurization tower, so the return ratio of this part is not limited, and any ratio can be set according to the actual emission situation.

[0053] The dust removal components include a bag dust collector, a slag powder finished product bin, a vertical mill induced draft fan and a vertical mill chimney; the inlet of the bag dust collector is connected to the low-temperature gas discharge port of the vertical roller mill device, the particle outlet of the bag dust collector is connected to the inlet of the slag powder finished product bin, the gas outlet of the bag dust collector is connected to the inlet of the vertical mill induced draft fan, the outlet of the vertical mill induced draft fan is connected to the vertical mill chimney, and as Figure 1 As shown, the outlet of the vertical mill induced draft fan is not connected to any gas inlet of the vertical roller mill device.

[0054] Example 2

[0055] This embodiment is used to illustrate an example of implementing a method for utilizing the combined utilization device of the blast furnace hot blast stove waste heat and slag drying in Example 1. The overall process steps are also as follows. Figure 1 As shown:

[0056] (1) The 260°C high-temperature flue gas coming out of the hot blast furnace and after being denitrated by the denitrification device is diverted through the first three-way valve to obtain the first high-temperature flue gas and the second high-temperature flue gas. The first high-temperature flue gas is discharged into the fixed-bed dry desulfurization device for dry desulfurization to obtain desulfurized high-temperature gas. The second high-temperature flue gas is discharged into the spraying device for spraying with water medium and then the temperature is reduced to 170°C. It is then discharged into the dense phase coherent tower semi-dry desulfurization tower for semi-dry desulfurization. The gas obtained after the semi-dry desulfurization is then discharged into the desulfurization dust collector (bag dust collector) for dust removal and then discharged through the desulfurization induced draft fan. The desulfurized gas discharged from the desulfurization induced draft fan is diverted, part of the gas returns to the inlet of the desulfurization tower and re-enters the desulfurization tower, and the remaining gas is discharged through the hot blast furnace chimney (the return ratio is not limited and any ratio is acceptable).

[0057] (2) The desulfurized high-temperature gas obtained after dry desulfurization in step (1) is discharged into the air mixing chamber at a flow rate of 200,000 Nm 3 / h. (During the process, if the desulfurized high-temperature gas is under maintenance or fails, the blast furnace gas from the blast furnace gas network outlet and the combustion air discharged from the first combustion-supporting fan or the second combustion-supporting fan are discharged into the combustion furnace for combustion, and the high-temperature combustion gas obtained after combustion is discharged into the air mixing chamber. The flow rate introduced is 65000Nm 3 / h, and the final discharge flow rate is 232000Nm by reusing and enriching this part of the gas. 3 / h).

[0058] (3) The raw slag (the raw slag is the blast furnace quenched slag formed by water quenching the molten waste slag produced in the blast furnace ironmaking process. The processing capacity of this embodiment is 100 tons of slag per hour. The moisture content of the raw slag is 11 wt.%, the original temperature is 25°C, and the specific heat of the slag is 0.95 kJ / (kg·K)) is discharged into a vertical roller mill for crushing and grinding. At the same time, the desulfurized high-temperature gas (or high-temperature combustion gas in part of the time) obtained in step (2) is discharged into the vertical roller mill. The slag obtained in the crushing and grinding process is dried to obtain a solid-gas mixture.

[0059] (4) The solid-gas mixture is discharged into the bag filter for solid-gas separation, and the dust separation obtains solid dust particles and dust removal gas (the exhaust gas flow rate here is 232000Nm 3 / h).

[0060] (5) The resulting solid dust particles are discharged into the slag fine powder product bin to produce the slag fine powder product. The dust removal gas is discharged into the vertical mill chimney through the vertical mill induced draft fan for subsequent treatment. The measured yield of the slag fine powder product is 89.5 tons per hour, the moisture content is 0.12 wt.%, and the measured temperature of the dust removal gas is 105°C.

[0061] The heat balance of Example 2 was calculated:

[0062] The heat input is: the heat Q provided by the combustion of blast furnace gas 煤气 , Heat from waste heat of hot blast furnace (i.e. heat brought in by high-temperature desulfurized gas obtained after dry desulfurization) Q 余热 , and the heat Q brought in by the slag raw materials 原料 .

[0063] The output heat is: the heat brought out by the exhaust (including the heat of water vapor entering the gas after evaporation) Q 外排 , the heat Q brought out by heat exchange (heat dissipation) between the system and the environment 热损 , and the heat Q brought out by the finished powder产品 .

[0064] Therefore, the thermal balance relationship of the system in this embodiment is:

[0065] Q 煤气 +Q 原料 +Q 余热 =Q 外排 +Q 产品 +Q 热损 .

[0066] where Q 热损 is a fixed value, and the examples and comparative examples can be offset.

[0067] Right now:

[0068] Q 煤气 =Q 外排 +Q 产品 -Q 原料 -Q 余热

[0069] =36180000kJ / h+8877750kJ / h-27136656kJ / h-2113750kJ / h

[0070] =2279344kJ / h.

[0071] After calculation:

[0072] Gas consumption = Q 煤气 / calorific value of blast furnace gas;

[0073] =2279344kJ / h / 3500kJ / Nm 3

[0074] =651Nm 3 / h

[0075] That is, the heat provided by blast furnace gas combustion can be completely replaced by the waste heat of hot blast stove (only 651Nm per hour is consumed). 3 The heat of blast furnace gas is basically equivalent to complete replacement).

[0076] Comparative Example 1

[0077] This comparative example adopts the existing water slag drying system for implementation. The overall device is Figure 1 The middle and lower part does not include a fixed-bed dry desulfurization device. Instead, the hot air from the combustion chamber is added to the air mixing chamber, and the exhaust gas from the vertical mill induced draft fan is returned to the air mixing chamber for heat recovery. The raw material is 100t of slag with the same hourly processing capacity as in Example 2, with a moisture content of 11%, a temperature of 25°C, and a calorific value of blast furnace gas of 3500kJ / Nm 3, water slag specific heat: 0.95kJ / (kg·K). By adjusting the drying temperature, the same finished product after drying is obtained: 89.1h, moisture content: 0.5%, exhaust gas temperature: 105℃, exhaust gas flow rate: 232000Nm 3 / h.

[0078] The thermal balance relationship of the system is:

[0079] Q 煤气 +Q 原料 =Q 外排 +Q 产品 +Q 漏风 +Q 热损 .

[0080] where Q 热损 is a fixed value, and the examples and comparative examples can be offset.

[0081] Right now:

[0082] Q 煤气 =Q 外排 +Q 产品 -Q 原料

[0083] =27136656+8877750-2113750

[0084] =33900656kJ / h

[0085] After calculation:

[0086] Gas consumption = Q 煤气 / calorific value of blast furnace gas;

[0087] =33900656 / 3500;

[0088] =9685Nm 3 / h.

[0089] That is, the hourly consumption of blast furnace gas under this production state is calculated to be: 9685Nm 3 / h.

[0090] Under the condition that all production conditions (product output, air flow in the mill) remain unchanged, the blast furnace gas consumption changes, that is, the hot blast furnace flue gas provides heat.

[0091] According to the energy balance and gas flow balance, that is:

[0092] Gas flow × calorific value released by gas combustion + calorific value released by hot blast furnace flue gas = total calorific value required by the system.

[0093] (Gas flow after combustion + hot air and flue gas introduction) / 0.9 = fan air volume.

[0094] Comparing the above calculation process, it can be seen that compared with Example 1, after waste heat utilization, the blast furnace gas can basically be replaced by the waste heat of the hot blast stove (the amount of gas saved is 9685-651=9034Nm 3 / h, and 9034 / 9685 = 93.28%). The present invention uses blast furnace gas as backup heat. The above calculations show that, overall, under normal conditions, the arrangement of the present invention can reduce energy consumption by nearly 94% compared to the original process (Comparative Example 1). It can essentially completely replace the original combustion gas drying process in Comparative Example 1, significantly improving energy conservation and consumption reduction.

[0095] The technical principles and examples of the present invention are described above in conjunction with specific embodiments. The above-mentioned embodiments and comparative examples of the present invention are all examples and do not limit the scope of protection of the technical solution. The technical effects that are not compared can be clearly described through the textual description of the technical effects, and do not mean that the invention is low. These descriptions are only for explaining the principles and examples of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations here, those skilled in the art can think of other specific embodiments of the present invention without paying creative labor, and these methods will fall within the scope of protection of the present invention.

Claims

1. A device for combining waste heat from a blast furnace hot blast stove with slag drying, characterized in that: It includes a fixed-bed dry desulfurization device, an air mixing chamber, a vertical roller mill, dust removal components and a combustion furnace; The combustion furnace is used to burn blast furnace gas and then discharge high-temperature combustion gas; The inlet end of the fixed bed dry desulfurization device is connected to the outlet end of the hot blast furnace denitrification device, and the connection position is located at the front end of the water spray cooling device; The air mixing chamber is used to discharge the high-temperature gas after internal mixing, and includes a first hot air inlet, a second hot air inlet, and a mixed air outlet; the first hot air inlet is connected to the outlet end of the fixed bed desulfurization device, and the second hot air inlet is connected to the combustion gas outlet of the combustion furnace; The vertical roller mill is used to crush, grind and dry the slag. The vertical roller mill is provided with a slag inlet, a high-temperature gas inlet and a low-temperature gas outlet. The slag inlet is used to discharge the raw slag, and the high-temperature gas inlet is only connected to the mixed air outlet of the air mixing chamber. The dust removal component is used for performing dust removal operation on the gas discharged from the low-temperature gas discharge port of the vertical roller mill device.

2. The device for combined utilization of waste heat from hot blast furnaces and slag drying according to claim 1, characterized in that: The fixed-bed dry desulfurization device is a radial fixed-bed desulfurization tower, comprising a tower body, an air inlet chamber, an air collecting chamber, a fixed bed layer and a supporting structure; the tower body is a multi-layer concentric cylindrical structure, with an air inlet chamber provided on the outside of the tower body, an air collecting chamber provided in the center of the tower body, and an annular fixed bed layer provided between the air inlet chamber and the air collecting chamber; the fixed bed layer is filled with granular desulfurizer, and a grid or a porous plate is provided at the bottom of the fixed bed layer as a supporting structure to support the desulfurizer particles.

3. The device for combined utilization of waste heat from hot blast furnaces and slag drying according to claim 1, characterized in that: The combined utilization device of blast furnace hot blast stove waste heat and slag drying also includes one or more combustion-supporting fans; the combustion furnace includes a combustion-supporting gas inlet, a blast furnace gas inlet and a combustion gas outlet, the combustion-supporting gas inlet is connected to the combustion-supporting fan, the blast furnace gas inlet is connected to the exhaust outlet of the blast furnace gas pipeline network, and the combustion gas exhaust outlet discharges the high-temperature combustion gas after combustion.

4. The device for combined utilization of waste heat from hot blast furnaces and slag drying according to claim 1, characterized in that: The device for combining waste heat from a blast furnace hot blast stove with slag drying also includes a denitrification device, a spraying device, a desulfurization tower, and a desulfurization dust collector; the denitrification device is used to denitrify the flue gas discharged from the hot blast stove; the spraying device is used to spray water medium to cool the high-temperature flue gas after the denitrification treatment; A three-way valve is provided on the pipeline after the denitrification device and before the spraying device. The inlet of the three-way valve is connected to the outlet of the denitrification device, the first outlet of the three-way valve is connected to the inlet end of the fixed-bed dry desulfurization device, and the second outlet of the three-way valve is connected to the inlet end of the spraying device; the desulfurization dust collector is used to remove dust from the flue gas after desulfurization.

5. The device for combined utilization of waste heat from hot blast furnaces and slag drying according to claim 4, characterized in that: The desulfurization tower is a dense phase coherent tower semi-dry desulfurization tower; the desulfurization dust collector is a bag dust collector.

6. The device for combined utilization of waste heat from hot blast furnaces and slag drying according to claim 1, characterized in that: The dust removal components include a bag dust collector, a slag micropowder finished product bin, a vertical mill induced draft fan and a vertical mill chimney; the inlet of the bag dust collector is connected to the low-temperature gas discharge port of the vertical roller mill device, the particle outlet of the bag dust collector is connected to the inlet of the slag micropowder finished product bin, the gas outlet of the bag dust collector is connected to the inlet of the vertical mill induced draft fan, the outlet of the vertical mill induced draft fan is connected to the vertical mill chimney, and the outlet of the vertical mill induced draft fan is not connected to any gas inlet of the vertical roller mill device.

7. A method for combining the utilization of waste heat from a blast furnace hot blast stove with slag drying, characterized in that: The steps include: (1) The high-temperature flue gas coming out of the hot blast furnace and after being denitrated by the denitrification device is split through a three-way valve to obtain a first high-temperature flue gas and a second high-temperature flue gas. The first high-temperature flue gas is discharged into a fixed-bed dry desulfurization device for dry desulfurization, and the second high-temperature flue gas is discharged into a spraying device for spraying with a water medium and then discharged into a desulfurization tower for desulfurization. The gas obtained after desulfurization is then discharged into a desulfurization dust collector for dust removal and then discharged through a desulfurization induced draft fan; (2) introducing the desulfurized high-temperature gas obtained after dry desulfurization in step (1) into the air mixing chamber. When the flow rate of the desulfurized high-temperature gas is insufficient or fails, the blast furnace gas discharged from the blast furnace gas network and the combustion-supporting air discharged from the combustion-supporting blower are discharged into the combustion furnace for combustion, and the high-temperature combustion gas obtained after the combustion is introduced into the air mixing chamber; The ratio of the volume flow rate of the desulfurized high-temperature gas introduced into the air mixing chamber to the volume flow rate of the high-temperature combustion gas introduced into the air mixing chamber is (2.3-3.5):1; (3) discharging the raw material slag into a vertical roller mill for crushing and grinding, and simultaneously discharging the desulfurized high-temperature gas and / or high-temperature combustion gas in the air mixing chamber of step (2) into the vertical roller mill to dry the slag from the crushing and grinding process to obtain a solid-gas mixture; (4) The solid-gas mixture is discharged into a bag filter for solid-gas separation, and the dust separation obtains solid dust particles and dust-removed gas; (5) The obtained solid dust particles are discharged into the slag micropowder finished product bin to obtain slag micropowder products; the dust removal gas is discharged into the vertical mill chimney through the vertical mill induced draft fan for subsequent treatment.

8. The method for combined utilization of blast furnace hot blast stove waste heat and slag drying according to claim 7, characterized in that: The method for combined utilization of waste heat from a blast furnace hot blast stove and slag drying is carried out by using the device for combined utilization of waste heat from a blast furnace hot blast stove and slag drying as described in any one of claims 1 to 6.

9. The method for combined utilization of blast furnace hot blast stove waste heat and slag drying according to claim 7, characterized in that: The temperature of the high-temperature flue gas after denitration treatment in the denitration device after exiting the hot blast furnace in step (1) is 256-298°C; the temperature of the flue gas discharged into the desulfurization tower is 166-178°C; The ratio of the volume flow rates of the first high-temperature flue gas and the second high-temperature flue gas in step (1) is (1-3):(7-9); In step (2), the gas discharged from the air mixing chamber is desulfurized high-temperature gas, high-temperature combustion gas, or a mixture of the two; The ratio between the amount of raw material water slag added and the amount of desulfurized high temperature gas added in step (3) is (95-106 tons): (153000-225000Nm 3 / h); The moisture content of the raw material slag in step (3) is 9-13wt.%, and the moisture content of the slag powder product obtained in step (5) is 0.06-0.15wt.%.

10. The method for combined utilization of blast furnace hot blast stove waste heat and slag drying according to claim 7, characterized in that: The raw material water slag in step (3) is blast furnace water-quenched slag formed by water quenching of molten waste slag produced during blast furnace ironmaking.

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