Submerged arc furnace stokehole floor mold pouring and iron slag separation waste heat recovery power generation system

Abstract

The invention relates to the technical field of submerged arc furnace waste heat recovery and utilization, and discloses a submerged arc furnace stokehole floor mold pouring and iron slag separation waste heat recovery power generation system. Comprising the following modules and components: a pretreatment and system initialization module, a shunting separation and primary heat exchange module, an iron slag deep cooling and sensible heat recovery module, a flue gas gathering heat exchange and power generation module and a tail end closed loop and waste heat secondary utilization module. The pretreatment and system initialization module comprises a chemical water system, a DCS (Distributed Control System), a temperature sensor, a pressure sensor, a flue gas flowmeter, an external circulating fan, a cold air regulating valve and a radiant heat exchange pipeline; the system can effectively recycle waste heat and radiant heat generated in the cooling process of molten iron and iron slag of the chromite heat furnace, efficient recycling of heat energy is achieved, meanwhile, the environment temperature of a production workshop is reduced, and a safe, environment-friendly and fresh-air working environment is provided for production workers.

Description

Technical Field

[0001] This invention relates to the field of waste heat recovery and utilization technology of submerged arc furnaces, and in particular to a waste heat recovery and power generation system for submerged arc furnace front-furnace casting and slag separation. Background Technology

[0002] Ferrochrome furnaces are an indispensable piece of equipment in the special steel metallurgy industry. The recovery and utilization of residual heat resources is of great significance for reducing energy consumption and environmental pollution. At present, although ferrochrome furnace flue gas waste heat recovery power generation systems can meet certain heat recovery needs, there are still some problems, such as low utilization rate of residual heat in iron slag during furnace casting and slag-iron separation. Moreover, producing 1 ton of ferrochrome generates 0.6-0.8 tons of iron slag. In particular, the high-temperature radiant heat generated during the slag-iron separation process during casting poses safety hazards to the working environment and human health at the production site. Existing waste heat recovery systems typically employ a conventional intake duct for the molten iron casting flue gas, connected to a dust collector via a circulating fan, a return duct for the annular cooler, and only recovering the flue gas from the electric arc furnace. While this system can achieve some particulate matter recovery, it still has some shortcomings: First, the waste heat from casting slag and iron was not recovered, resulting in a waste of the heat carried by the slag and iron during casting. Second, the heat carried by the slag and iron was dissipated into the production workshop in the form of radiant heat, which had a particularly large impact on the working environment of the workers. Workers who were in this environment for a long time were prone to health problems. Therefore, there is an urgent need to develop a new type of waste heat recovery system for molten iron and slag poured in front of the submerged arc furnace to solve the problems existing in the current technology. This system can effectively recover and utilize the waste heat and radiant heat generated during the cooling process of molten iron and slag in the ferrochrome submerged arc furnace, realize the efficient recovery and utilization of thermal energy, and at the same time reduce the ambient temperature of the production workshop, providing a safe, environmentally friendly and fresh working environment for production workers. Summary of the Invention

[0003] The purpose of this invention is to provide a waste heat recovery and power generation system for casting and slag separation in front of a submerged arc furnace. This system can effectively recover and utilize the waste heat and radiant heat generated during the cooling process of molten iron and slag in a ferrochrome submerged arc furnace, achieving efficient heat energy recovery and utilization. At the same time, it reduces the ambient temperature of the production workshop, providing a safe, environmentally friendly, and fresh working environment for production workers.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A waste heat recovery and power generation system for casting and slag separation in front of a submerged arc furnace includes the following modules and components: The system includes a pretreatment and system initialization module, a diversion and primary heat exchange module, an iron slag deep cooling and sensible heat recovery module, a flue gas collection heat exchange and power generation module, and a tail-end closed-loop and waste heat secondary utilization module. The pretreatment and system initialization module includes: a water treatment system, a DCS control system, a temperature sensor, a pressure sensor, a flue gas flow meter, an external circulating fan, a cold air regulating valve, and a radiant heat exchange pipe. The diversion and primary heat exchange module includes: a grate machine, a small waste heat recovery channel fume hood, a ground-mounted radiant heat recovery fume hood, radiant heat exchange pipes, an external circulating fan, and a cold air regulating valve. The iron slag deep cooling and sensible heat recovery module includes: a grate cooler, a crusher, and a high-temperature flue gas outlet; The flue gas collection, heat exchange, and power generation module includes: flue gas collection pipeline, air control valve, waste heat boiler, bag filter, exhaust fan, and condensing steam turbine generator set; The tail-end closed-loop and waste heat secondary utilization module includes: a condenser, a thermal deaerator, an ash removal system, and workshop heating branch pipes.

[0005] As a further improvement to this technical solution: the water treatment system includes a softening device, a desalination device, and a thermal deaerator, which sequentially perform softening, desalination, and thermal deaeration treatments. The water supply conductivity is ≤0.1μS / cm, the oxygen content after deaeration is ≤0.05mg / L, and the thermal deaerator pressure is maintained at 0.02-0.05MPa. The DCS control system receives the operating data of each device and presets the waste heat boiler pressure at 3.5MPa and the turbine generator speed at 3000 rpm. The temperature sensor, pressure sensor, and flue gas flow meter collect flue gas temperature, boiler pressure, and flue gas flow data, respectively. The external circulating fan introduces ambient temperature air, which is preheated in conjunction with the radiant heat exchange pipes. The cold air regulating valve has an initial opening of 30% to control the fan's airflow. The radiant heat exchange pipes are used to receive high-temperature flue gas and achieve heat transfer.

[0006] As a further improvement to this technical solution: the slag grate machine is equipped with a grate plate with an aperture of 8-10cm for separating molten iron and slag; the small waste heat recovery channel fume hood is equipped with a high-temperature resistant insulation layer and castable refractory inside, with an external insulation layer thickness of 6cm, connecting the iron tapping port of the electric arc furnace to the slag grate machine; the ground mold radiant heat recovery fume hood encloses the area above the ground mold, with several parallel radiant heat exchange pipes arranged inside, connected by heat-resistant steel sheets between the pipes, and a 10-15cm insulation layer between the pipes and the fume hood; the radiant heat exchange pipes are arranged in a straight-through manner, with a gas distribution box connected to the top, and the gas distribution box gradually increases in size from far to near; the external circulating fan and the cold air regulating valve work together to adjust the opening according to the formula α=30%+k×(T-800℃), where α is the opening of the cold air valve with an upper limit of 80%, T is the real-time temperature of the flue gas, and k is the adjustment coefficient with a value of 0.05% / ℃.

[0007] As a further improvement to this technical solution: the grate cooler includes a high-pressure cooling fan, an alloy grate bed, and a hydraulic system; the high-pressure cooling fan delivers air at a speed of 8-12 m / s; the alloy grate bed is heat-resistant up to 1300℃ and includes fixed grate plates and movable grate plates; the hydraulic system drives the movable grate plates to reciprocate at 10-15 times / minute; the crusher is used to crush blocky iron slag into granular materials with a diameter <3 cm; the high-temperature flue gas outlet is used to collect the high-temperature flue gas generated during the iron slag cooling process.

[0008] As a further improvement to this technical solution: the flue gas collection pipeline connects to the flue gas outlets of the ground-mounted radiant heat recovery hood, slag remover, and grate cooler; the air control valve opens to 80% when a single furnace is tapping iron, and distributes air volume at a ratio of 30-35% per furnace when multiple furnaces are operating in tandem; the waste heat boiler adopts a membrane wall structure with multiple layers of heat exchange pipes inside, a pressure rating of 3.2-3.82 MPa, and an outer composite insulation structure consisting of an outer layer of color steel plate and an inner layer of refractory insulation material; the bag filter has multiple layers of filter bags inside and is equipped with an ash removal system at the bottom; the exhaust fan is a centrifugal structure, connecting the bag filter to the chimney; the condensing steam turbine generator set has a pressure rating of 2.5 MPa, is equipped with a DEH automatic control system, a speed of 3000 rpm, an exhaust pressure of 0.08-0.1 MPa, and its output shaft is connected to the generator.

[0009] As a further improvement to this technical solution: the condenser is used to condense the exhaust steam from the turbine into water; the thermal deaerator receives the condensate discharged from the condenser and removes oxygen again; the ash removal system collects the dust filtered by the bag filter and discharges it; the workshop heating branch pipe is connected to the flue gas outlet of the grate cooler, and is activated in winter to introduce heat into the workshop.

[0010] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention effectively recovers the waste heat generated during the simultaneous cooling of molten iron and the treatment of iron slag, converting the originally wasted heat energy into usable electrical energy, which greatly improves the comprehensive utilization rate of energy and reduces the ineffective consumption of energy. At the same time, the iron slag can be reused as a resource after treatment, reducing the emission of solid waste; the flue gas is discharged after purification, reducing the impact on the environment; and the water vapor is recycled and reused in the system, which also reduces the consumption of water resources. Overall, it is more in line with the needs of green production.

[0011] 2. This invention relies on an automated control system to achieve coordinated operation of various devices, reducing manual intervention, improving the stability and safety of system operation, and reducing the risk of operational errors. At the same time, its parallel layout design of multiple sets of equipment can adapt to the linkage operation scenarios of multiple submerged arc furnaces, making it more widely applicable. The independent functions and linkage logic of each module not only ensure the efficient advancement of core processes such as waste heat recovery and power generation, but also help extend the service life of the equipment and reduce long-term maintenance costs.

[0012] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Specific embodiments of the present invention are given in detail below with reference to the accompanying drawings. Attached Figure Description

[0013] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the system structure of a waste heat recovery and power generation system for casting the ground mold in front of a submerged arc furnace and separating iron slag. The system includes: main equipment: chromite ore arc furnace (1, 1b, 1c), slag grate machine (2, 2b, 2c), grate cooler (3, 3b, 3c), cast-in-place formwork (4, 4b, 4c), formwork fume hood (5, 5b, 5c), waste heat boiler (6), dust collector (7), exhaust fan (8), condensing steam turbine generator set (9), softened water deaerator (10); Auxiliary equipment: chrome ferrofluidic air distribution box (11, 11b, 11c), external circulating fan (12, 12b, 12c), ground-mounted fume hood radiant heat collection membrane wall pipe (13, 13b, 13c), several grate coolers (14, 14b, 14c), grate cooler head crusher (15, 15b, 15c), fan motor (16), generator (17), chimney (18); Iron and slag flow channels: connecting pipes between the electric arc furnace and the slag grate machine (21, 21b, 21c), flow channels from the slag grate machine to the ground mold (22, 22b, 22c), flow channels from the slag grate machine to the grate cooler (23, 23b, 23c), and slag discharge channels (24, 24b, 24c); Flue gas flow direction pipelines: flue gas outlet of ground mold fume hood (31, 31b, 31c), grate machine outlet pipeline (32, 32b, 32c), grate cooler outlet pipeline (33, 33b, 33c), flue gas collection connection pipeline (34, 34b, 34c), grate cooler cold air pipeline (35, 35b, 35c), boiler outlet to dust collector pipeline (36), dust collector to exhaust fan pipeline (37), exhaust fan to chimney pipeline (38); Steam and water transmission pipelines: steam pipeline from boiler to condensing steam turbine generator set (41), water supply pipeline from deaerator to waste heat boiler (42), and low-pressure steam pipeline from condensing steam turbine generator set to deaerator exhaust heating (43). Electrical automation control system: monitoring electrical components, valve control components, automatic control components, connection lines, main power input and output lines, DCS system, DEH steam control system. Detailed Implementation

[0014] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. The invention is described more specifically in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0015] Please see Figure 1 In this embodiment of the invention, a waste heat recovery and power generation system for casting the ground mold in front of a submerged arc furnace and separating iron slag includes the following modules and components: The system includes a pretreatment and system initialization module, a diversion and primary heat exchange module, an iron slag deep cooling and sensible heat recovery module, a flue gas collection heat exchange and power generation module, and a tail-end closed-loop and waste heat secondary utilization module. The pretreatment and system initialization module includes: water treatment system, DCS control system, temperature sensor, pressure sensor, flue gas flow meter, external circulating fan, cold air regulating valve, and radiant heat exchange pipe; The diversion and primary heat exchange module includes: a grate machine, a small waste heat recovery channel fume hood, a ground-mounted radiant heat recovery fume hood, radiant heat exchange pipes, an external circulating fan, and a cold air regulating valve. The iron slag deep cooling and sensible heat recovery module includes: a grate cooler, a crusher, and a high-temperature flue gas outlet; The flue gas collection, heat exchange, and power generation module includes: flue gas collection pipeline, air control valve, waste heat boiler, bag filter, exhaust fan, and condensing steam turbine generator set; The tail-end closed-loop and waste heat secondary utilization module includes: condenser, thermal deaerator, ash removal system, and workshop heating branch pipes; Specifically, the pretreatment and system initialization module is the preparation and basic guarantee module before system startup. Its components include water treatment, control, monitoring and preheating equipment, which provide stable preconditions for subsequent waste heat recovery. The flow separation and primary heat exchange module is the core module for realizing the separation of molten iron and slag and the initial heat energy recovery. The components are designed around flow separation, flue gas collection and heat exchange to complete the first stage of heat energy capture. Iron slag deep cooling and sensible heat recovery module: This module focuses on iron slag cooling and sensible heat extraction. The components are used for rapid cooling, morphological processing and high-temperature flue gas collection of iron slag, maximizing the recovery of the heat energy carried by the iron slag. Flue gas collection, heat exchange and power generation module: The core module of the system's energy conversion. The component is responsible for the collection of flue gas, the conversion of heat energy, steam energy and electrical energy, and the purification of flue gas to achieve the final goal of power generation; Tail-end closed-loop and waste heat secondary utilization module: The system resource recycling and waste heat reuse module is used for water vapor circulation, solid waste treatment and additional waste heat utilization, forming a closed-loop ecosystem. The water treatment system includes a softening unit, a desalination unit, and a thermal deaerator, which sequentially perform softening, desalination, and thermal deaeration treatments. The water supply conductivity is ≤0.1μS / cm, and the oxygen content after deaeration is ≤0.05mg / L. The thermal deaerator pressure is maintained at 0.02-0.05MPa. The DCS control system receives the operating data of each device and presets the waste heat boiler pressure at 3.5MPa and the turbine generator speed at 3000 rpm. Temperature sensors, pressure sensors, and flue gas flow meters collect flue gas temperature, boiler pressure, and flue gas flow data, respectively. An external circulating fan introduces ambient temperature air, which is preheated in conjunction with the radiant heat exchange pipes. The cold air regulating valve has an initial opening of 30% to control the fan's airflow. The radiant heat exchange pipes are used to receive high-temperature flue gas and achieve heat transfer. Specifically, the water treatment system consists of a softening unit, a desalination unit, and a thermal deaerator. It processes the water supply in the order of softening, desalination, and thermal deaeration. The conductivity of the water supply is controlled to ≤0.1μS / cm to prevent scale formation inside the waste heat boiler caused by impurities in the water. The oxygen content after deaeration is ≤0.05mg / L, preventing oxidation and corrosion of pipes and boiler components. The thermal deaerator pressure is maintained at 0.02-0.05MPa to ensure a stable and efficient deaeration process, providing the system with clean and qualified circulating water. DCS control system: It receives the operating data of all equipment, presets the waste heat boiler pressure to 3.5MPa and the turbine generator speed to 3000 rpm, and is the control center for the automated operation of the system, used to uniformly schedule the parameters of each component; Temperature sensor, pressure sensor, and flue gas flow meter: respectively collect flue gas temperature, boiler pressure, and flue gas flow data to provide precise control basis for the DCS control system; External circulating fan: introduces ambient temperature air and works with radiant heat exchange pipes to complete the preheating operation, avoiding damage to the pipes caused by sudden cooling of high temperature flue gas; Cold air regulating valve: The initial opening is set to 30%. Its core purpose is to control the airflow of the fan and to dynamically adjust it in accordance with subsequent operating conditions. Radiant heat exchange pipes: As a carrier of heat energy transfer, they receive the high-temperature flue gas introduced later, realizing the initial heat transfer and pipe preheating.

[0016] The slag grate machine is equipped with a grate plate with an aperture of 8-10cm for separating molten iron and slag. The small waste heat recovery channel fume hood is equipped with a high-temperature resistant insulation layer and castable refractory inside, and the external insulation layer is 6cm thick. It connects the iron tapping hole of the electric arc furnace to the slag grate machine. The ground mold radiant heat recovery fume hood encloses the area above the ground mold. Several parallel radiant heat exchange pipes are arranged inside. The pipes are connected by heat-resistant steel sheets. A 10-15cm insulation layer is installed between the pipes and the fume hood. The radiant heat exchange pipes are arranged in a straight line and connected to the top of the gas distribution box. The gas distribution box gradually increases in size from far to near. The external circulating fan and the cold air regulating valve work together to adjust the opening according to the formula α=30%+k×(T-800℃), where α is the opening of the cold air valve with an upper limit of 80%, T is the real-time temperature of the flue gas, and k is the adjustment coefficient with a value of 0.05% / ℃. Specifically, the slag grate machine is equipped with a grate plate with an aperture of 8-10cm. Its core purpose is to separate molten iron and slag through physical screening, so that the molten iron flows to the ground mold and the slag flows to the grate cooler, creating conditions for the recovery of waste heat. Small waste heat recovery channel fume hood: The interior is equipped with a high-temperature resistant insulation layer and castable material, and the external insulation layer is 6cm thick. It is specially designed to connect the iron tapping hole of the electric arc furnace and the slag grate. Its structural design can minimize the heat loss of high-temperature flue gas between the iron tapping hole and the slag grate, and accurately guide the flue gas into the subsequent heat exchange components, solving the problem of unorganized emission of flue gas in this section in the traditional system. Ground model radiant heat recovery fume hood: used to enclose the area above the ground model, with several parallel radiant heat exchange pipes arranged inside. The pipes are connected by heat-resistant steel sheets, and a 10-15cm insulation layer is set between the pipes and the fume hood. The enclosed structure can collect the radiant heat emitted when the molten iron is cooled. The insulation layer can reduce the heat loss to the outside. The heat-resistant steel sheets connecting the pipes can improve the stability of the pipes and ensure efficient capture of radiant heat. Radiant heat exchange pipes: They adopt a straight-through layout, with the top connected to the gas distribution box. The gas distribution box gradually increases in size from far to near. The straight-through design extends the contact path between the flue gas and the pipes. The gradual structure of the gas distribution box allows cold air to be evenly distributed to each pipe, ensuring heat exchange uniformity and improving heat exchange efficiency. External circulating fan and cold air regulating valve: The two work together to adjust the opening of the cold air valve according to the formula α=30%+k×(T-800℃). The symbols in the formula are: α is the opening of the cold air valve, with an upper limit set at 80%; T is the real-time temperature of the flue gas (unit: ℃); k is the adjustment coefficient, with a value of 0.05% / ℃. The core function of the formula is to dynamically adjust the air supply flow based on the real-time temperature of the flue gas. When the flue gas temperature is higher than 800℃, the opening increases proportionally with the temperature increase, introducing more cold air to balance the heat exchange intensity. This not only avoids damage to the pipeline due to overheating, but also heats the cold air into hot air and blows it onto the surface of the molten iron, realizing the conversion of radiative heat to convective heat.

[0017] The grate cooler includes a high-pressure cooling fan, an alloy grate bed, and a hydraulic system; the high-pressure cooling fan delivers air at a speed of 8-12 m / s; the alloy grate bed is heat-resistant up to 1300℃ and includes fixed and movable grate plates; the hydraulic system drives the movable grate plates to reciprocate at 10-15 times / minute; the crusher is used to crush lumpy iron slag into granular materials with a diameter of <3 cm; the high-temperature flue gas outlet is used to collect the high-temperature flue gas generated during the iron slag cooling process; Specifically, the grate cooler consists of a high-pressure cooling fan, an alloy grate bed, and a hydraulic system. The high-pressure cooling fan delivers air at a speed of 8-12 m / s to rapidly cool the liquid iron slag flowing into the grate cooler to a solid state. The alloy grate bed is resistant to temperatures up to 1300℃ and includes fixed and movable grate plates, capable of withstanding the direct impact of high-temperature iron slag. The hydraulic system drives the movable grate plates to reciprocate at 10-15 times per minute, uniformly pushing the iron slag forward to ensure thorough cooling without dead zones, while also efficiently recovering the sensible heat carried by the iron slag. Crusher: Its core purpose is to crush cooled blocky iron slag into granular materials with a diameter of <3cm, which facilitates subsequent recycling as building material. High-temperature flue gas outlet: Its core purpose is to collect the high-temperature flue gas generated during the cooling process of iron slag, and to introduce the flue gas carrying sensible heat into the subsequent flue gas collection pipeline to realize the secondary transfer of heat energy.

[0018] The flue gas collection pipeline connects to the flue gas outlets of the ground-mounted radiant heat recovery hood, slag remover, and grate cooler; the air control valve opens to 80% when a single furnace is tapping iron, and distributes the air volume to each furnace at a ratio of 30-35% when multiple furnaces are operating in tandem; the waste heat boiler adopts a membrane wall structure with multiple layers of heat exchange pipes inside, a pressure rating of 3.2-3.82MPa, and an outer composite insulation structure with an outer layer of color steel plate and an inner layer of refractory insulation material; the bag filter has multiple layers of filter bags inside and is equipped with an ash removal system at the bottom; the exhaust fan is a centrifugal structure, connecting the bag filter to the chimney; the condensing steam turbine generator set has a pressure rating of 2.5MPa, is equipped with a DEH automatic control system, a speed of 3000 rpm, an exhaust pressure of 0.08-0.1MPa, and its output shaft is connected to the generator; Specifically, the flue gas collection pipeline: its core purpose is to connect the flue gas outlets of the ground model radiant heat recovery hood, grate machine, and grate cooler, and to collect the high-temperature flue gas generated by each module in order to prepare for subsequent centralized heat exchange. Air control valve: When tapping iron from a single furnace, the opening is set to 80%. When multiple furnaces are working together, the air volume is distributed according to the ratio of 30-35% of each furnace. Its core purpose is to regulate the flue gas flow of each branch, ensure the flue gas load is stable, and avoid local overpressure or uneven heat exchange. Waste heat boiler: It adopts a membrane wall structure with multiple layers of heat exchange pipes inside, and a pressure rating of 3.2-3.82MPa. The outer side is a composite insulation structure of an outer layer of color steel plate and an inner layer of refractory insulation material. The membrane wall structure can increase the heat exchange area and improve the heat energy conversion efficiency. The multiple layers of heat exchange pipes are used to fully transfer the heat energy of flue gas to circulating water to generate superheated steam. The composite insulation structure can reduce the heat loss inside the boiler and ensure the steam generation efficiency. Baghouse dust collector: It has multiple layers of filter bags inside and is equipped with a dust discharge system at the bottom. Its core purpose is to capture particulate matter in flue gas, purify flue gas, and prevent dust emissions from polluting the environment. Exhaust fan: It is a centrifugal structure that connects the bag filter and the chimney. Its core purpose is to provide power for flue gas circulation, maintain the negative pressure environment inside the system, and ensure the smooth transmission of flue gas from the boiler to the chimney. Condensing steam turbine generator set: pressure rating 2.5MPa, equipped with DEH automatic control system, speed 3000 rpm, exhaust pressure 0.08-0.1MPa, output shaft connected to generator. DEH automatic control system is used to regulate steam intake to ensure stable operation of the unit; the speed of 3000 rpm can match the 50Hz frequency of the power grid, ensuring the quality of output power; by receiving superheated steam generated by waste heat boiler, it converts thermal energy into mechanical energy, and then drives the generator through the output shaft to convert it into electrical energy, which is the core equipment of the power generation system.

[0019] The condenser is used to condense the exhaust steam from the turbine into water; the thermal deaerator receives the condensate from the condenser and removes oxygen again; the ash removal system collects the dust filtered by the bag filter and discharges it; the workshop heating branch pipe is connected to the flue gas outlet of the grate cooler, and is put into use in winter to introduce the workshop heating. Specifically, the condenser's core function is to condense the exhaust steam from the turbine into water, facilitating subsequent recycling and reuse, and reducing water consumption. Thermal deaerator: It receives condensate discharged from the condenser and deoxygenates it again. Its core purpose is to ensure that the circulating water always meets the system water standards and to prevent impurities or oxygen from damaging the equipment. Ash removal system: Its core purpose is to collect the dust filtered by the bag filter and discharge it centrally. The collected dust can be recycled as an auxiliary raw material for smelting in an electric arc furnace. Workshop heating branch pipe: Connects to the flue gas outlet of the grate cooler. It is activated in winter and introduced into the workshop for heating. Its core purpose is to recover the residual heat of the flue gas discharged from the grate cooler to provide heating for the production workshop, realize the secondary utilization of waste heat, and further reduce the overall energy consumption of the system.

[0020] The method of use and working principle of this invention are as follows: Operating Instructions: First, start the electrical automation control system and related auxiliary equipment to complete system initialization and equipment preheating. After the blast furnace finishes tapping iron, the molten iron and slag enter the grate cooler through corresponding connecting pipes to achieve separate processing. The molten iron flows into the casting mold through a dedicated channel, while the slag enters the grate cooler. Then, start the mold fume hood, various fans, and other equipment to collect the radiant heat emitted during the cooling of the molten iron and the heat from the flue gas generated when the slag is cooled in the grate cooler. This flue gas is collected through various outlet pipes and introduced into the waste heat boiler. The waste heat boiler uses the heat from the flue gas to generate steam, which is then transported to the turbine generator set to complete the power generation operation. At the same time, the steam and water are circulated and reused between the waste heat boiler, deaerator, and turbine generator set through dedicated pipelines. After the slag is processed by the grate cooler, it is further processed by the head crusher. The purified flue gas is discharged through the chimney. After the operation is completed, shut down the relevant equipment to complete the system's final operation.

[0021] Working Principle: Starting with the separation of molten iron and slag, a grate cooler separates the molten iron and slag discharged from the submerged arc furnace. While the molten iron cools in the casting mold, the mold's fume hood and associated heat collection pipes collect its radiant heat. The slag, after entering the grate cooler, is cooled by a cooling fan, and the grate cooler also recovers the sensible heat carried by the slag. The flue gas generated in each stage is collected through corresponding flue gas flow pipes and then introduced into a waste heat boiler. The heat energy of the flue gas is converted into steam energy in the waste heat boiler, and the steam is transported to a steam turbine generator set, further converting the steam energy into electrical energy. Simultaneously, water and steam circulate through dedicated pipelines between the waste heat boiler, deaerator, and steam turbine generator set, achieving water resource reuse. The entire process relies on an electrical automation control system to regulate the equipment's operating status and the flow direction of various media, ensuring coordinated operation of all modules and completing the entire process of waste heat recovery and power generation.

[0022] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Those skilled in the art can readily implement the present invention based on the description and drawings above. However, any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention using the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A waste heat recovery and power generation system for casting and slag separation in front of a submerged arc furnace, characterized in that, Includes the following modules and components: The system includes a pretreatment and system initialization module, a diversion and primary heat exchange module, an iron slag deep cooling and sensible heat recovery module, a flue gas collection heat exchange and power generation module, and a tail-end closed-loop and waste heat secondary utilization module. The pretreatment and system initialization module includes: a water treatment system, a DCS control system, a temperature sensor, a pressure sensor, a flue gas flow meter, an external circulating fan, a cold air regulating valve, and a radiant heat exchange pipe. The diversion and primary heat exchange module includes: a grate machine, a small waste heat recovery channel fume hood, a ground-mounted radiant heat recovery fume hood, radiant heat exchange pipes, an external circulating fan, and a cold air regulating valve. The iron slag deep cooling and sensible heat recovery module includes: a grate cooler, a crusher, and a high-temperature flue gas outlet; The flue gas collection, heat exchange, and power generation module includes: flue gas collection pipeline, air control valve, waste heat boiler, bag filter, exhaust fan, and condensing steam turbine generator set; The tail-end closed-loop and waste heat secondary utilization module includes: a condenser, a thermal deaerator, an ash removal system, and workshop heating branch pipes.

2. The waste heat recovery and power generation system for pre-furnace casting and slag separation in a submerged arc furnace according to claim 1, characterized in that, The water treatment system includes a softening device, a desalination device, and a thermal deaerator, which sequentially perform softening, desalination, and thermal deaeration treatments. The water supply conductivity is ≤0.1μS / cm, and the oxygen content after deaeration is ≤0.05mg / L. The thermal deaerator pressure is maintained at 0.02-0.05MPa. The DCS control system receives operating data from each device and presets the waste heat boiler pressure at 3.5MPa and the turbine generator speed at 3000 rpm. Temperature sensors, pressure sensors, and flue gas flow meters collect flue gas temperature, boiler pressure, and flue gas flow data, respectively. An external circulating fan introduces ambient temperature air, which is preheated in conjunction with the radiant heat exchange pipes. The cold air regulating valve has an initial opening of 30% to control the fan's airflow. The radiant heat exchange pipes are used to receive high-temperature flue gas and achieve heat transfer.

3. The waste heat recovery and power generation system for pre-furnace casting and slag separation in a submerged arc furnace according to claim 1, characterized in that, The slag grate machine is equipped with a grate plate with an aperture of 8-10cm for separating molten iron and slag. The small waste heat recovery channel fume hood is equipped with a high-temperature resistant insulation layer and castable refractory inside, and the outer insulation layer is 6cm thick. It connects the iron tapping hole of the electric arc furnace to the slag grate machine. The ground mold radiant heat recovery fume hood encloses the area above the ground mold and arranges several parallel radiant heat exchange pipes inside. The pipes are connected by heat-resistant steel sheets, and a 10-15cm insulation layer is installed between the pipes and the fume hood. The radiant heat exchange pipes are arranged in a straight-through manner and connected to a gas distribution box at the top. The gas distribution box gradually increases in size from far to near. The external circulating fan and the cold air regulating valve work together to adjust the opening according to the formula α=30%+k×(T-800℃), where α is the opening of the cold air valve with an upper limit of 80%, T is the real-time temperature of the flue gas, and k is the adjustment coefficient with a value of 0.05% / ℃.

4. The waste heat recovery and power generation system for pre-furnace casting and slag separation in a submerged arc furnace according to claim 1, characterized in that, The grate cooler includes a high-pressure cooling fan, an alloy grate bed, and a hydraulic system; the high-pressure cooling fan delivers air at a speed of 8-12 m / s; the alloy grate bed is heat-resistant up to 1300℃ and includes fixed and movable grate plates; the hydraulic system drives the movable grate plates to reciprocate at 10-15 times / minute; the crusher is used to crush blocky iron slag into granular materials with a diameter <3 cm; the high-temperature flue gas outlet is used to collect the high-temperature flue gas generated during the iron slag cooling process.

5. The waste heat recovery and power generation system for pre-furnace casting and slag separation in a submerged arc furnace according to claim 1, characterized in that, The flue gas collection pipeline connects to the flue gas outlets of the ground-mounted radiant heat recovery hood, slag remover, and grate cooler; the air control valve opens to 80% when a single furnace is tapping iron, and distributes air volume at a ratio of 30-35% per furnace when multiple furnaces are operating in tandem; the waste heat boiler adopts a membrane wall structure with multiple layers of heat exchange pipes inside, a pressure rating of 3.2-3.82 MPa, and an outer composite insulation structure consisting of an outer layer of color steel plate and an inner layer of refractory insulation material; the bag filter has multiple layers of filter bags inside and is equipped with an ash removal system at the bottom; the exhaust fan is a centrifugal structure, connecting the bag filter to the chimney; the condensing steam turbine generator set has a pressure rating of 2.5 MPa, is equipped with a DEH automatic control system, a speed of 3000 rpm, an exhaust pressure of 0.08-0.1 MPa, and its output shaft is connected to the generator.

6. The waste heat recovery and power generation system for casting the pre-furnace mold and separating iron slag in a submerged arc furnace according to claim 1, characterized in that, The condenser is used to condense the exhaust steam from the turbine into water; the thermal deaerator receives the condensate from the condenser and deaerates it again; the ash removal system collects and discharges the dust filtered by the bag filter. The workshop heating branch pipe is connected to the flue gas outlet of the grate cooler and is put into use in winter to supply heating to the workshop.

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