Liquid blast furnace slag granulation and waste heat recovery system and method

Abstract

A liquid blast furnace slag granulation and waste heat recovery system and method, which comprises a cyclone heat exchange device, a granulation device, and a waste heat recovery device. The granulation device injector sprays compressed air and water into high-speed jets to shear the molten blast furnace slag falling freely into the flow hood from the slag tank, and the molten blast furnace slag is broken and solidified into solid particles under the shearing and impact of the high-speed jets. The granulated blast furnace slag enters the cyclone heat exchanger with high-temperature air and steam to achieve rapid separation. The deoxygenated water is pressurized by a hot water pump and then sent to the spiral pipe bundle to exchange heat with the high-temperature gas outside the pipe to obtain saturated or superheated steam, which is delivered to the second heat exchanger of the waste heat recovery device. The high-temperature slag separated from the gas enters the first heat exchanger, and the heat exchange pipe bundle in the first heat exchanger drum is supplied with cooling water to absorb the heat of the high-temperature slag and convert it into steam, and the temperature of the high-temperature slag is further reduced to below 100 DEG C. The low-temperature slag particles flow out from the bottom of the waste heat recovery device and are sent out for recycling by a conveying device.

Description

Technical Field

[0001] The present invention belongs to the technical field of metallurgical slag granulation and waste heat recovery, and in particular relates to a liquid blast furnace slag granulation and waste heat recovery system and method. Background Art

[0002] Blast furnace slag is a solid waste produced during the steelmaking process. Its main components include CaO, MgO, Al₂O₃, and MnO. The tapping temperature of blast furnace slag is 1400-1600°C. Each ton of blast furnace slag carries approximately 1770MJ of heat energy, equivalent to 60kg of standard coal, offering significant potential for heat recovery.

[0003] To achieve resource utilization of blast furnace slag, the most common blast furnace slag treatment method in my country is currently water slag flushing. For example, Ren Yubin and others employed a water slag flushing process that combines a granulation tower with a dehydrator and centralized steam discharge. This process uses a pressurized water jet from the granulation system to rapidly quench and granulate the molten slag. The resulting slag-water mixture enters the granulation tower, where it is fully buffered and water quenched. It then flows through a water slag ditch into the dehydration device's screen bucket, where it enters the dehydration process. The high-temperature steam generated during the granulation process is discharged into the air through a chimney above the gas collector (Ren Yubin, "Design of a Water Slag Flushing System for Shougang Changgang's No. 9 Blast Furnace." Jiangxi Building Materials, 2021, 04:238-24).

[0004] Although the glassy blast furnace slag produced by this method can be used in the cement industry for resource utilization, the overall treatment system consumes a lot of water. For every ton of slag processed, 3 tons of slag flushing water is consumed, 0.7 tons of water is replenished per ton of slag, and the slag power consumption is 3kW·h / ton of slag. At the same time, a large amount of waste steam rich in pollutants such as H2S and SO2 is emitted. In addition, the process adopts a direct flue gas discharge treatment method, and the waste heat recovery efficiency of the flue gas is 0.

[0005] In the subsequent resource utilization, the water in the slag needs to be dried, and 1 ton of slag requires 1200m 3 The 500°C hot air (see Chinese patent CN112146446A, "Blast furnace slag granulation and heat exchange device based on multi-media coupling") consumes approximately 0.1 kW·h / ton of slag. Therefore, a blast furnace slag granulation and waste heat recovery system should meet the following requirements: 1) a rational granulation process to address high water consumption and severe pollution; 2) a rational waste heat recovery system to address low waste heat recovery efficiency; and 3) a small overall system footprint, compact equipment, stable operation, and easy maintenance.

[0006] In order to solve the problem of high water consumption in water-washing slag and reduce the generation of harmful gases, dry granulation can be used. Zou Youwu and others introduced the comprehensive recovery technology of sensible heat of blast furnace slag jointly developed by six major companies including Kawasaki Steel Corporation of Japan. The slag enters the wind tunnel from the chute and is blown away by the granulating wind and broken into particles. The cooling circulating air is blown into the wind tunnel to cool the slag particles to 800℃ and then discharged from the wind tunnel. After the discharged granulated slag is screened out of large particles by the hot screen, it is stored in a high-temperature funnel and then undergoes secondary heat exchange in a multi-stage fluidized bed to further cool the granulated slag to about 150℃ (Zou Youwu, "Comprehensive recovery technology of sensible heat of blast furnace slag developed by Japan", Anshan Iron and Steel Technology, 1990, 10: 3-14). The air volume required for wind quenching and granulation of equipment with a processing capacity of 100t / h of high-temperature slag is 4000m 3 / h, circulating cooling air volume is 3100m 3 / min(186000m 3 / h), and the wind pressure is calculated as 0.2MPa, the fan power is calculated to be about 40kW·h / ton of slag (Xu Kuichang. Fan Manual [M]. Beijing: Machinery Industry Press, 2011: 21-22). In this process, the following problems exist:

[0007] 1) Liquid slag is granulated using air, and the air consumption is huge, about 190,000m 3 / h, the power consumption is about 40kW·h / ton slag, which is about 13 times that of the water slag flushing method.

[0008] The granulation, heat exchange and gas-solid separation devices in the system occupy a large area. First, the main dimensions of the wind tunnel used for granulation and primary heat exchange are: 25m long, 7m wide and 13m high; secondly, the cyclone dust collector in the system is used to collect 190,000m 3 / h gas for separation and dust removal, taking the average velocity of the dust collector cylinder clearance section as 2.5m / s, the diameter of the cyclone dust collector cylinder is about 5200mm (Zhang Dianyin. Dust Collector Manual [M]. Beijing: Chemical Industry Press, 2014: 114).

[0009] 3) When the slag flow rate changes, the wind speed and air volume are difficult to coordinate, and a large amount of cold air entering the system also reduces the residual recovery efficiency.

[0010] The air quenching granulation and waste heat recovery technologies for blast furnace slag were developed from the air quenching granulation process jointly developed by six major companies including Kawasaki Steel Corporation of Japan; subsequent improved patents include HATCH's U.S. patents US 20170297113A1 and US20170137912A1, and U.S. patents US6,803,016B2 and US2002 / 0117786A1 invented by Alfred Edlinger et al.

[0011] Chinese patent CN202530095U discloses a centrifugal molten slag dry granulation and waste heat recovery power generation system. The system described in the patent includes a slag receiving device, a slag centrifugal rapid cooling and granulation device, a slag slow cooling device, a waste heat recovery power generation device and an exhaust gas purification and treatment device. The molten slag is rapidly cooled and granulated by a unique centrifugal granulation device and quickly cooled into a glassy state, and then further slowly cooled and heat-exchanged by a water-cooled vibrating grate, and then steam is generated by a waste heat boiler to drive the steam turbine generator set to generate power. According to the data provided in the patent, the blast furnace slag becomes droplets under the centrifugal force of the rotating cup and exchanges heat with the cooling air input by the blower. 1) If the initial temperature of the blast furnace slag is 1500℃ and the mass flow rate is 2t / min, the air absorbs heat and the temperature rises from 25℃ to 850℃. According to the heat balance principle, the cooling air volume is calculated to be approximately 103122m 3 / h, and the wind pressure is calculated as 0.2MPa, which gives a fan power of approximately 18kW·h / ton of slag. 2) When the rotor speed is 3000r / min and the slag flow rate is 2t / min, the required motor power is 0.1-0.125kW·h / ton of slag (Sun Peng. Current Status and Prospects of Comprehensive Utilization of Blast Furnace Slag [J]. Ansteel Technology, 2008, 3: 6-9). The power consumption during blast furnace slag granulation is approximately 18.1kW·h / ton of slag, which is approximately 0.45 times the power consumption of air quenching granulation, and the energy consumption is lower than that of air quenching granulation. However, the slag centrifugal quenching granulation device in this system occupies a large area. The diameter of the slag centrifugal quenching granulation device with a processing capacity of only 40t / h is 4.2m. If the slag mass flow rate is 100t / h, three slag centrifugal quenching granulation devices with a diameter of 4.2m are required in parallel (Li Shun. Domestic and foreign molten blast furnace slag sensible heat recovery methods [J]. Industrial Heating, 2009, 38(03): 1-4). At the same time, the high-speed rotating cup is in direct contact with the high-temperature slag, which reduces the reliability of the granulation equipment operation. In addition, the granulation effect is more sensitive to the temperature and flow changes of the liquid blast furnace slag. The granulation quality is unstable and slag wool is easily formed during the rotation process. The effect of adjusting the speed alone is not ideal. The high-temperature slag concentrates and hits a certain part inside the equipment at high speed, which can easily cause local overheating of the equipment and damage the equipment. At present, the dry granulation method is still in the experimental research stage and has not yet been industrialized (Liu Meng. Current status and trend of blast furnace slag treatment technology [J]. Metallurgical Equipment, 2021, 266: 1-4).

[0012] Chinese patent CN108060279A discloses a method combining dry granulation and water quenching granulation. A motor drives the granulation cup to rotate, causing the slag inside the cup to be ejected and formed into small droplets. The droplets are cooled by cooling water sprayed from a water sprinkler to form slag particles, which fall through the discharge port onto a conveyor and are then transported. Cooling water that is not vaporized during the granulation process flows back to the water collection tank, and the vaporized water vapor enters the water vapor waste heat recovery system, where its heat is utilized. This invention still uses centrifugation as the initial granulation method. The high-temperature slag directly erodes the surface of the granulation cup, causing the rotating cup to burn and deform, making it unable to operate stably for a long time. Furthermore, acidic gases such as SO2 and H2S generated by water quenching enter the waste heat recovery system without being treated. Long-term operation can cause severe corrosion of the waste heat recovery equipment, posing a safety hazard to production.

[0013] Chinese patent CN101550460A discloses a method and device for rapid cooling of blast furnace slag and waste heat recovery. The device uses fluidized air to carry the blast furnace slag into a cyclone separator to achieve gas-solid separation. At the same time, the dual cooling system of fluidized air and water-cooled walls around the gas-solid separator rapidly cools the blast furnace slag to achieve a rapid cooling effect; the separated blast furnace slag enters a storage tank, and fluidized air is introduced into the bottom of the storage tank to put it in a bubbling bed state for further cooling; the air and cooling water are pressurized and then enter the boiler to achieve waste heat recovery. From the perspective of granulation, this method belongs to a typical air quenching granulation process, but because the air density is small and the impact force is small, the air volume and pressure required for granulating the molten slag are very large. The total gas consumption in this process is 5000m 3 / h, the outlet air pressure is calculated as 0.2MPa, and the fan power is about 12kW·h / ton of slag. From a structural point of view, the invention mainly uses fluidized air and water-cooled walls to achieve rapid cooling of blast furnace slag. Due to the low thermal conductivity of air, the heat transfer efficiency of the inter-wall type is much lower than that of the direct contact type. The high-temperature slag droplets formed by air blowing directly adhere to the water-cooled wall, reducing the heat transfer effect, resulting in a gradual decrease in the glass conversion rate of the blast furnace slag, affecting the safe operation of the system and the resource utilization of the blast furnace slag. In addition, the vortex core phenomenon exists in the entire space of the gas-solid separator, and there is an eccentric longitudinal circulation near the dust outlet at the bottom of the separator. These conditions may cause the particles that have been separated to the wall and flow down to the dust outlet along with the downward flow to be accidentally drawn into the upward internal vortex, thereby causing the particles to be mixed back (Wang Lu. Influence of inlet structure and air velocity on the non-steady-state characteristics of the internal vortex flow in the cyclone separator [D]. Taiyuan University of Technology, 2018). In the structure of this invention, the storage tank and the gas-solid separator are directly connected, which easily causes the fluidized air introduced at the lower end of the storage tank to carry the separated blast furnace slag back to the gas-solid separator, reducing the gas-solid separation efficiency. In addition, the fluidized air will carry a large number of small-diameter particles into the waste heat boiler. If a large amount of soot accumulates on the heating surface of the boiler, it will not only affect the heat exchange efficiency of the boiler and reduce steam production, but also threaten the long-term safe operation of the boiler (Wang Guozhen. Reduce soot adhesion and improve the heat exchange efficiency of waste heat boilers [J]. Copper Engineering, 2021, 03: 31-33). From the perspective of waste heat recovery, air is a poor conductor of heat, with a thermal conductivity of only 0.023W / m·k, which is much smaller than the thermal conductivity of water (0.59W / m·K). In this invention, air is used as a cooling medium, and the temperature of the hot air obtained by heat exchange with the slag is only 300°C, and the waste heat recovery efficiency is low.

[0014] In addition, there are many ways to recover the heat from the high-temperature flue gas generated during the slag cooling process.

[0015] For example, Chinese patent CN1212870632U discloses a flue gas waste heat recovery system. A cooling medium flows from an inlet into a heat exchange structure. A water-cooled wall and a coiled tube heat exchange structure covering the cylinder and / or tube walls absorb the heat energy generated by the flue gas at the cylinder and / or tube walls. After absorbing the heat energy, the cooling medium flows out of the outlet and can be reused in various ways, thereby achieving waste heat recovery. Structurally, gas mixed with dust enters the cyclone separator through the inlet pipe. Solid particles in the gas directly impact the outer tube wall inserted into the cyclone separator cavity. Over long periods of operation, the heat exchange tubes wrapped around the outer tube wall are prone to cracking, leading to cooling medium leakage and compromising the safe operation of the system. From the perspective of waste heat recovery, the coiled tubes are only distributed on the tube wall, not fully utilizing the space within the tube. The heat exchange area is limited, and most of the heat in the flue gas is discharged without being recovered, resulting in a waste of resources.

[0016] Xu Peng et al. proposed a shell-and-tube heat exchange cyclone dust collector, in which a heat pipe bundle is inserted into the cyclone dust collector. The dust-laden flue gas is purified by the dust collector and heat exchanged by the heat pipe at the same time, thereby achieving the purpose of heat exchange and dust removal (Xu Peng. Numerical simulation of high-efficiency heat pipe heat exchange cyclone dust collector [J]. Industrial Furnace, 2013, 35(01): 9-12). The document analyzes the distribution of the cyclone field, separation efficiency and pressure drop under a certain inlet Reynolds number, cyclone structure size and tube bundle structure size. It does not systematically analyze the influence of different inlet Reynolds numbers and cyclone structure size on the flow field distribution, separation efficiency and pressure drop in the cyclone separator; nor does it link the cyclone separator structure parameters, different inlet Reynolds numbers and tube bundle structure parameters with the tube bundle heat exchange effect. The structure has a certain degree of improvement in the graded dust removal efficiency for solid particles with a particle size of 5 to 13 μm, but the article lacks experimental verification on the effective recovery of flue gas heat by the structure. In addition, from a structural point of view, this structure uses straight tubes for heat exchange. Compared with spiral tubes or serpentine tubes, the heat exchange area of ​​straight tubes is much smaller within the same tube diameter and space. Summary of the Invention

[0017] The purpose of the present invention is to provide a liquid blast furnace slag granulation and waste heat recovery system and method to solve the problems of high water consumption, serious pollution, low waste heat recovery efficiency and large system footprint of blast furnace slag granulation in the prior art. It has the advantages of low energy consumption and low pollution granulation function, fast and efficient gas-solid separation and waste heat recovery function.

[0018] To achieve the above object, the technical solution of the present invention is:

[0019] A liquid blast furnace slag granulation and waste heat recovery system, comprising a cyclone heat exchange device, a granulation device, and a waste heat recovery device; wherein,

[0020] The cyclone heat exchange device comprises:

[0021] Cyclone heat exchanger, comprising:

[0022] The cylinder has a feed port and a feed channel on one side of its upper part, and the lower part of the cylinder is conical, with a slag discharge port and a discharge valve at its bottom; preferably, the discharge valve is a star-shaped discharge valve;

[0023] The overflow pipe has its lower part vertically inserted into the upper part of the cylinder; the top of the overflow pipe is provided with a high-temperature dust-laden gas outlet;

[0024] The spiral tube bundle is arranged in the overflow pipe, and the two ends of the spiral tube bundle, namely the tube bundle water inlet and the tube bundle air outlet, are located outside the overflow pipe;

[0025] The steam drum has an inlet connected to the deaerated water pipeline, a deaerated water outlet connected to the water inlet of the spiral tube bundle through a pipeline and a hot water pump, and a gas outlet connected to the steam drum; the steam outlet on the steam drum is connected to the steam pipe network;

[0026] The granulation device includes an ejector and a flow guide cover; the ejector outlet corresponds to the flow guide cover inlet, and the flow guide cover outlet is connected to the cyclone heat exchanger feed channel of the cyclone heat exchange device; the top surface of the flow guide cover is provided with a slag inlet;

[0027] The ejector includes an ejector provided with a compressed air interface and a water interface, the compressed air interface and the water interface are connected to a compressed air pipe and a water pipe respectively; the ejector outlet is connected to the guide cover inlet; preferably, the ejector is a Venturi ejector;

[0028] The waste heat recovery device is arranged below the cyclone heat exchange device and includes:

[0029] The first heat exchanger is a drum-type heat exchanger, comprising a drum and a drive motor; a feed port and a discharge port are provided at each end of the drum, the feed port being connected to the slag discharge port of the cyclone heat exchanger cylinder; a water inlet connected to the deaerated water pipeline is provided at one end of the drum provided with the feed port, and a steam outlet is provided at the other opposite end; a heat exchange tube bundle is provided within the drum, the inlet of the heat exchange tube bundle being connected to the deaerated water pipeline, and the outlet of the heat exchange tube bundle, i.e., the steam outlet, being connected to the steam pipe network; a conveyor device for conveying slag particles is provided below the drum discharge port; the conveyor device is preferably a belt conveyor;

[0030] The second heat exchanger includes a cylinder with an exhaust gas inlet and an exhaust gas outlet at both ends respectively; the exhaust gas inlet is connected to the high-temperature dust-containing gas outlet at the top of the overflow pipe through a pipeline; a heat exchange tube is arranged in the second heat exchanger, and the two ends of the heat exchange tube are a water inlet and a steam outlet; the water inlet is connected to the deoxygenated water pipeline, and the steam outlet is connected to the steam network or the user; preferably, the heat exchange tube adopts a serpentine structure.

[0031] Furthermore, a desulfurization and dust removal device is provided, which includes an alkali liquid tank, a circulation pump, a nozzle, a washing tower, a liquid storage tank, a liquid removal tower, an induced draft fan, and a chimney;

[0032] A deliquidation tower, wherein a deliquidator is provided in the middle or upper part thereof; a liquid outlet is provided at the lower part of the deliquidation tower and is connected to the inlet pipe of the circulation pump; a gas outlet is provided at the top of the deliquidation tower and is connected to a chimney through a pipe and an induced draft fan for discharge to the atmosphere;

[0033] The inlet end of the washing tower is connected to the top of the overflow pipe of the cyclone heat exchanger or the tail gas outlet of the second heat exchanger through a pipeline; the lower part of the washing tower is provided with a liquid storage tank for storing alkali solution, and the outlet end of the liquid storage tank is connected to the deliquescence tower;

[0034] The outlet end of the alkali liquid tank is connected to the nozzle through a pipeline and a circulation pump. The nozzle is arranged in the upper middle part of the washing tower.

[0035] Furthermore, a steam grinding device is provided, which includes a steam turbine and a grinding device; the inlet of the steam turbine is connected to the steam outlet of the first heat exchanger and the steam outlet of the second heat exchanger through a pipeline; the conveying device for transporting the slag particles below the discharge port of the first heat exchanger drum is connected to the feed port of the grinding device, and the discharge port of the grinding device is transported to the user.

[0036] Preferably, an air cushion and a water cushion are provided in the feed channel of the cylinder of the cyclone heat exchanger, and the inlets of the air cushion and the water cushion are connected to compressed air and water respectively; preferably, the air cushion and the water cushion are narrow grooves that are provided in the 1 / 4 arc of the circumferential tangential inlet from the upper part of the side wall of the cylinder of the cyclone heat exchanger and pass through the cylinder, and the inlets of the air cushion and the water cushion are connected to compressed air and water respectively.

[0037] Preferably, the side walls of the cylinder of the cyclone heat exchanger are respectively an insulating wear-resistant lining, a water-cooled wall, and a steel plate from the inside to the outside; the insulating wear-resistant lining is preferably made of silicon carbide material; preferably, the water-cooled wall is provided with a water-cooled wall cold water inlet connected to the deaeration water pipeline, and the water-cooled wall hot water outlet is connected to the steam drum inlet.

[0038] Preferably, the upper part of the cylinder of the cyclone heat exchanger is a cylindrical cylinder, and the lower part is an inverted conical cylinder; preferably, the angle between the generatrix of the inverted conical cylinder and the horizontal plane is 20-80°, preferably 20-60°, or more preferably 20-40°.

[0039] Preferably, the overflow pipe is a circular tube of equal diameter or a tube with an upper diameter 1 to 2 times the lower diameter and an enlarged upper portion.

[0040] In the liquid blast furnace slag granulation and waste heat recovery system of the present invention:

[0041] The cyclone heat exchanger is used to recover heat from the heat exchange between granulating gas and high-temperature slag. The granulation unit is used to transport and granulate the molten slag. The waste heat recovery unit is used to recover heat from the slag and transport the low-temperature tailings. The desulfurization and dust removal unit is used to purify and discharge the exhaust gas. The steam grinding unit is used to grind the slag into slag powder, which is used as the main raw material for cement and fertilizer production.

[0042] The cyclone heat exchange device primarily comprises a cyclone heat exchanger, a spiral tube bundle, a steam drum, and a hot water pump. Deoxygenated water is delivered to the steam drum, and the hot water pump is connected to the steam drum and the spiral tube bundle at its head and tail, respectively. The spiral tube bundle is housed within an overflow pipe, with its inlet connected to the hot water pump and its outlet connected to the steam drum. The bottom slag outlet of the cyclone heat exchanger is connected to a discharge valve. An air cushion and a water cushion are located at the inlet of the cyclone heat exchanger. A water-cooled wall is located outside the cylinder of the cyclone heat exchanger. The inlet of the cyclone heat exchanger is connected to a shroud.

[0043] The air cushion and water cushion are narrow grooves provided on the wall surface of the inlet tube of the cyclone heat exchanger. The inlets of the air cushion and water cushion are connected to compressed air and water respectively, which are used to sweep the blast furnace slag to prevent the unsolidified high-temperature slag particles from sticking to the wall.

[0044] The cyclone heat exchanger consists of an overflow pipe and a coaxially arranged cylinder, which includes a cylindrical section and a conical section. The cylinder is divided into three layers along its thickness: an insulating and wear-resistant lining, a water-cooled wall, and carbon steel or low-alloy steel. The insulating and wear-resistant lining is designed to operate normally at temperatures between 1000°C and 1500°C and exhibits high wear and impact resistance. Silicon carbide or CoCrAlTaY is preferred.

[0045] The water-cooled wall is used to improve the impact resistance and wear resistance of the lining, solve the problem of lining shedding, and recover the heat of the high-temperature slag.

[0046] The granulation device includes an ejector and a shroud. Compressed air and water are connected to the gas inlet and water inlet of the ejector, respectively. The ejection end face is connected to the shroud inlet. A slag inlet is provided just above the shroud inlet end face. A manhole for maintenance is provided near the end face connecting the shroud and the cyclone heat exchanger. The shroud is connected to the cyclone heat exchanger inlet.

[0047] The waste heat recovery device includes a first heat exchanger and a second heat exchanger. The first heat exchanger is a drum-type heat exchanger, comprising a motor and a drum. The drum houses a cylindrical heat exchange tube bundle. Deoxygenated water flows through the heat exchange tube inlet, and steam is fed into the steam network through the outlet. Low-temperature slag falls from the slag discharge port at the bottom of the first heat exchanger drum onto a conveyor. The second heat exchanger is equipped with heat exchange tubes, which are fed with deoxygenated water. Steam flows through the outlet into a steam grinding device. The exhaust gas after heat exchange enters a desulfurization and dust removal device for purification.

[0048] The desulfurization and dust removal device includes an alkali liquid tank, a circulation pump, a scrubber, a liquid storage tank, a deliquescence tower, a nozzle, an induced draft fan, and a chimney. The alkali liquid tank is connected to the circulation pump, which is connected to the nozzle, which is located on the scrubber. The liquid storage tank is located directly below the scrubber and is connected to the scrubber and deliquescence tower, respectively. The induced draft fan is connected to the gas outlet pipe at the top of the deliquescence tower and discharges the gas into the chimney.

[0049] The steam grinding device includes a steam turbine and a grinding unit. Saturated or superheated steam produced by a cyclonic heat exchanger and waste heat recovery unit enters the steam turbine, where the thermal energy is converted into kinetic energy, driving the grinding unit to grind the heat-exchanged blast furnace slag particles into powder, which serves as the primary raw material for cement production.

[0050] The present invention also provides a method for using the liquid blast furnace slag granulation and waste heat recovery system, wherein compressed air and water enter the ejector cavity through the gas and water interfaces on the granulation device ejector respectively, mix, form a high-speed jet and enter the guide cover, shear the molten blast furnace slag that freely falls from the slag pot into the guide cover, and the molten blast furnace slag is broken and solidified into solid particles under the shearing and impact of the high-speed jet; the granulated blast furnace slag enters the cyclone heat exchanger along with the high-temperature air and water vapor, and the large density difference between the gas and solid phases is utilized to achieve rapid separation in the cyclone heat exchanger; the deoxygenated water is pressurized by the hot water pump and transported to the spiral tube, and heat-exchanged with the high-temperature gas outside the tube to obtain saturated or superheated steam, which is transported to the waste heat recovery device the second heat exchanger; the high-temperature slag after separation from the gas enters the first heat exchanger of the waste heat recovery device through the discharge valve, and cooling water is introduced into the heat exchange tube bundle in the drum of the first heat exchanger. The liquid water quickly absorbs the heat of the high-temperature slag in the drum and converts it into water vapor. The temperature of the high-temperature slag is further reduced to below 100°C, and the low-temperature slag particles flow out from the bottom of the waste heat recovery device and are transported out by the conveyor for recycling; preferably, the low-temperature blast furnace slag particles are transported by the conveyor to the steam grinding device, and the saturated or superheated water vapor generated by the first heat exchanger and the second heat exchanger enters the steam turbine, and the thermal energy is converted into kinetic energy, which drives the grinding device to grind the blast furnace slag particles after heat exchange into powder as the main raw material for producing cement.

[0051] The heat-exchanged gas then enters the desulfurization and dust removal unit. Alkali in the alkali tank is sprayed upwards into the airstream via a circulating pump, achieving efficient cleaning and purification. The washed mixed gas undergoes gas-liquid separation, with the liquid re-entering the storage tank for recycling. The purified gas then passes through a demister to remove entrained liquid before being discharged.

[0052] In the method of the present invention:

[0053] The granulation device described herein utilizes an ejector. Compressed air and water enter the ejector chamber, mixing to form a high-speed jet that then enters the deflector. This jet shears the molten blast furnace slag, which freely falls into the deflector after being discharged from the blast furnace. The shearing action of the high-speed jet breaks the molten slag into particles. The slag particles solidify on their surfaces after heat exchange with the air and water, while the interiors of the particles remain molten. The water vaporizes into water vapor, which absorbs heat and raises the temperature of the air. The slag particles, along with the high-temperature air and water vapor mixture, enter a cyclone heat exchanger. Within the cyclone heat exchanger, the mixed gas further contacts and exchanges heat with the slag particles, raising their temperature to 500°C and lowering the temperature of the slag particles to 700°C for complete solidification. The activity of the granulated blast furnace slag is primarily determined by its glass content. A high glass content can only be achieved if the cooling rate exceeds the critical cooling rate.

[0054] The slag of the present invention can be rapidly cooled, with a cooling rate of about 200°C / s, which is much higher than the critical cooling rate of 10°C / s. The granulated slag has a particle size distribution of 1-5 mm, is uniform in size, and has a glass content of up to 100%.

[0055] The glassy content in the granulated slag obtained by water quenching is 95% (Ren Yubin. Design of water slag flushing system for Shougang Changgang No. 9 blast furnace [J]. Jiangxi Building Materials, 2021, 04: 238-24).

[0056] The glassy content of the granulated slag obtained by the wind quenching method is 95% (Zou Youwu. Comprehensive recovery technology of sensible heat of blast furnace slag developed by Japan [J]. Anshan Iron and Steel Technology, 1990, 10: 3-14).

[0057] In a cyclonic flow field, the centrifugal force exerted on the dispersed phase is far greater than the gravitational force exerted on it. Furthermore, the dispersed phase only needs to migrate radially to the sidewalls of the cyclonic heat exchanger. Therefore, the separation speed, precision, and efficiency of a cyclonic heat exchanger are far superior to those of gravity sedimentation, and the equipment is also much smaller than gravity sedimentation equipment. By utilizing the significant density difference between the gas and solid phases, rapid separation is achieved within the cyclonic heat exchanger.

[0058] In addition, installing a spiral heat exchange tube in the overflow pipe of the cyclone heat exchanger achieves efficient heat recovery and utilization. Compared with the straight tube type, first of all, in terms of heat exchange, the spiral tube structure can substantially improve the heat transfer efficiency, especially for boiling and evaporation, the critical heat flux is significantly increased, and the local cross flow along the pipe (i.e., secondary circulation) and countercurrent heat exchange inside and outside the pipe can also improve its heat exchange capacity; secondly, the spiral tube structure can expand relatively freely, so it will not produce excessive thermal stress; finally, the arrangement of the spiral tube can ensure a compact design, thereby reducing the occupied space. Therefore, based on a comprehensive consideration of total cost, design and manufacturing experience, thermal performance and operating characteristics, spiral heat exchange tubes are preferred for heat exchange.

[0059] Deoxygenated water is pressurized by a hot water pump and then transported into the spiral tube, where it exchanges heat with the high-temperature gas outside the tube to produce saturated or superheated steam. For example, the present invention consumes 0.13 tons of water per ton of slag and has a water pump power of approximately 0.03 kW / h. Compared with traditional water slag flushing processes, this method uses only 4.3% of the water used, contributing to energy conservation and emission reduction for steel companies. This significant reduction in water consumption also reduces the production of acidic gases, thereby minimizing environmental pollution. If the compressor outlet pressure is calculated as 0.4 MPa, the compressor power is approximately 3 kW / h per ton of slag (Sinopec Shanghai Engineering Co., Ltd. Chemical Process Design Manual [M]. Beijing: Chemical Industry Press, 2018: 1275-1276). The total energy consumption during the slag granulation process is similar to that of the water slag flushing method, 8% of that of the air quenching method, and 17% of that of the centrifugal granulation method.

[0060] After the cyclonic heat exchange, the gas enters the second heat exchanger for further heat recovery. Deoxygenated water is introduced into the heat exchange tubes of the second heat exchanger, where it is exchanged with the high-temperature gas outside the tubes and vaporized into saturated or superheated steam. The exhaust gas after heat exchange enters the desulfurization and dust removal device for purification. Alkali liquid from the alkali liquid tank is sprayed upward through nozzles into the airflow via a circulating pump, achieving efficient scrubbing and purification. The washed mixed gas undergoes gas-liquid separation, with the liquid re-entering the liquid storage tank for recycling. The purified gas is then discharged through a demister to remove entrained liquid.

[0061] After separation from the gas, the high-temperature slag enters the first heat exchanger through a star-shaped discharge valve to further recover the slag's heat. Cooling water flows through the heat exchanger's heat exchanger tubes. The liquid water rapidly absorbs heat in the first heat exchanger and converts into steam, further reducing the slag temperature to below 100°C. The low-temperature slag particles flow out through the bottom of the first heat exchanger and are transported by a conveyor to the steam grinding unit.

[0062] The saturated or superheated steam produced by the cyclone heat exchanger, the first heat exchanger, and the second heat exchanger converge and enter the steam turbine, which converts the thermal energy of the steam into kinetic energy, driving the grinding device to grind the cooled slag into powder with a particle size of about 50μm, which is used as a raw material for producing cement or fertilizer.

[0063] The equipment of the present invention has a compact structure and occupies a small area, and can simultaneously realize effective separation of gas and solid and produce high-grade steam.

[0064] For example, if the diameter of the cyclone heat exchanger is designed to be Φ5500mm and the slag processing capacity is 2400t / d (the blast furnace generally has intermittent slag discharge with a cycle of 3h, of which the slag discharge time is 1h), the recovered heat can produce saturated or superheated water vapor, and can simultaneously achieve the separation of high-temperature gas and slag.

[0065] When the slag processing capacity in the water slag flushing process is 1128t / d, the diameter of the granulation tower body is Φ6000mm, and the high-temperature gas is directly discharged into the atmosphere, and heat recovery cannot be achieved in the granulation tower.

[0066] The wind quenching process processes 800 tons of slag per day (blast furnaces typically discharge slag intermittently, with a 3-hour cycle, including 1 hour of discharge time). The wind tunnel used for granulation and heat exchange measures 25 meters long, 7 meters wide, and 13 meters high. The cyclone dust collector used for gas-solid separation has a diameter of 5200 mm. Steam cannot be directly generated in the wind tunnel; additional boiler equipment is required for steam generation, resulting in a significantly larger overall equipment footprint than the cyclone heat exchanger described in this invention.

[0067] When the centrifugal process processes 320 tons of slag per day, processing a 2400 tons per day slag mass flow requires eight centrifugal quenching and granulation units with a diameter of 4200 mm in parallel. Steam cannot be directly generated in the centrifugal quenching and granulation units; additional waste heat boiler equipment is required to generate steam, resulting in a significantly larger overall equipment footprint than the cyclone heat exchanger of the present invention. Furthermore, effective gas-solid separation cannot be achieved in the centrifugal quenching and granulation units; the high-temperature gas carries some solid particles into the waste heat boiler, reducing the heat exchange efficiency and service life of the waste heat boiler.

[0068] The advantages of the present invention are:

[0069] The present invention is based on the micro-interface oscillation rapid cooling mechanism in the cyclonic field. By optimizing the structure of the cyclonic heat exchanger, the amplitude and frequency of the micro-interface oscillation are increased, so that the rapid cooling rate of the blast furnace slag is ≥200℃ / s, ensuring that the glassy content of the blast furnace slag after granulation and cooling is 100%, and at the same time enhancing the heat transfer and separation effect of the cyclonic heat exchanger. After the high-temperature slag particles enter the cyclonic heat exchanger, they pulsate and rotate to produce rapid oscillations. The interface oscillation is beneficial for thinning the thickness of the boundary layer, increasing the heat transfer coefficient and thus enhancing heat transfer; at the same time, the interface oscillation causes the local flow field around the slag particles to continuously change, allowing more cold air to contact the particle surface, increasing the heat exchange area and facilitating enhanced heat transfer; in addition, the interface oscillation is beneficial for the molecular motion of the molten state inside the slag particles, strengthening the relative flow inside the slag particles, realizing convective heat transfer inside the slag particles, improving the heat transfer coefficient and thus enhancing the heat exchange process.

[0070] 2) The cyclone heat exchanger of the present invention is based on a coupled design of cyclone desolidification and waste heat recovery, making full use of the advantage of the fast cyclone separation speed, so that the separation time of the gas-solid two-phase mixture is greatly shortened. Compared with the conventional system of first granulating and then removing dust and finally recovering heat through the waste heat boiler, its subsequent separation and heat exchange process is greatly shortened, and the number of equipment required by the system is significantly reduced. The cyclone heat exchanger has the advantages of great operational flexibility, high separation efficiency, high separation precision, high waste heat recovery efficiency, high space utilization, compact structure, small footprint, high economic benefits, and easy maintenance.

[0071] The system of the present invention is used for granulating high-temperature liquid slag and recovering heat. The slag temperature is 1400-1600°C, the rated mass flow rate is 300t / h, and the system operating pressure is -7kPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 This is a schematic diagram of the process flow of an embodiment of the liquid blast furnace slag granulation and waste heat recovery system according to the present invention;

[0073] Figure 2This is a schematic structural diagram of a cyclone heat exchange device and a granulation device in an embodiment of the liquid blast furnace slag granulation and waste heat recovery system of the present invention;

[0074] Figure 3 This is a schematic structural diagram of a waste heat recovery device and a steam grinding device in an embodiment of the liquid blast furnace slag granulation and waste heat recovery system of the present invention;

[0075] Figure 4 It is a structural schematic diagram of the desulfurization and dust removal device in an embodiment of the liquid blast furnace slag granulation and waste heat recovery system of the present invention. DETAILED DESCRIPTION

[0076] See also Figures 1 to 4 The liquid blast furnace slag granulation and waste heat recovery system of the present invention comprises a cyclone heat exchange device 100, a granulation device 200, and a waste heat recovery device 300; wherein,

[0077] The cyclone heat exchange device 100 includes:

[0078] The cyclone heat exchanger 1 comprises:

[0079] The cylinder 11 has a feed port and a feed channel 111 on one side of its upper portion. The lower portion of the cylinder 11 is conical, and a slag discharge port 112 and a discharge valve 113 are provided at its bottom. Preferably, the discharge valve 113 is a star-shaped discharge valve.

[0080] The overflow pipe 12 has its lower portion vertically inserted into the upper portion of the cylinder 11; a high-temperature dust-laden gas outlet 121 is provided at the top of the overflow pipe 12;

[0081] The spiral tube bundle 13 is disposed in the overflow pipe 12, and both ends of the spiral tube bundle 13, namely the tube bundle water inlet 131 and the tube bundle air outlet 132, are located outside the overflow pipe 12;

[0082] The steam drum 2 has its inlet connected to the deoxygenated water pipeline. The steam drum 2 is provided with a deoxygenated water outlet 201, which is connected to the tube bundle water inlet 131 of the spiral tube bundle 13 through a pipeline and a hot water pump 3. The tube bundle gas outlet 132 of the spiral tube bundle 13 is connected to the steam drum 2. The steam outlet 202 on the steam drum 2 is connected to the steam pipe network.

[0083] The granulating device 200 includes an ejector 4 and a flow guide 5; the ejector 4 outlet corresponds to the flow guide 5 inlet, and the flow guide 5 outlet is connected to the cyclone heat exchanger 1 feed channel 111 of the cyclone heat exchange device 100; the top surface of the flow guide 5 is provided with a slag inlet 51;

[0084] The ejector 4 includes an ejector provided with a compressed air interface 401 and a water interface 402, the compressed air interface and the water interface are connected to the compressed air pipe and the water pipe respectively; the ejector 4 outlet is connected to the guide cover 5 inlet; preferably, the ejector 4 is a Venturi ejector;

[0085] The waste heat recovery device 300 is disposed below the cyclone heat exchange device 100 and includes:

[0086] The first heat exchanger 6 is a drum-type heat exchanger comprising a drum 61 and a drive motor 62. A feed port 611 and a discharge port 612 are provided at both ends of the drum 61, respectively. The feed port 611 is connected to the slag discharge port 112 of the cylinder 11 of the cyclone heat exchanger 1. One end of the drum 61 having the feed port 611 is also provided with a water inlet 613 connected to the deaerated water pipeline, and the other end thereof is provided with a steam outlet 614. A heat exchange tube bundle 63 is provided within the drum 61. The inlet of the heat exchange tube bundle 63 is connected to the deaerated water pipeline, and the outlet of the heat exchange tube bundle 63, i.e., the steam outlet, is connected to the steam pipe network. A conveyor device 7 for conveying slag particles is provided below the discharge port 612 of the drum 61. The conveyor device 7 is preferably a belt conveyor.

[0087] The second heat exchanger 8 includes a cylinder 81, with an exhaust gas inlet 811 and an exhaust gas outlet 812 at both ends respectively; the exhaust gas inlet 812 is connected to the high-temperature dust-containing gas outlet 121 at the top of the overflow pipe 12 through a pipeline; a (serpentine) heat exchange tube 82 is set in the second heat exchanger 8, and the two ends of the heat exchange tube 82 are a water inlet 821 and a steam outlet 822; the water inlet 821 is connected to the deoxygenated water pipeline, and the steam outlet 822 is connected to the steam network or the user.

[0088] Furthermore, a desulfurization and dust removal device 400 is provided, which includes an alkali liquid tank 9, a circulation pump 10, a nozzle 16, a washing tower 17, a liquid storage tank 18, a liquid removal tower 19, an induced draft fan 20, and a chimney 21;

[0089] The deliquation tower 19 has a deliquator 191 in the middle or upper part thereof; a liquid outlet 192 is provided at the lower part of the deliquation tower 19 and is connected to the inlet pipe of the circulation pump 10; a gas outlet 193 is provided at the top of the deliquation tower 19 and is connected to the chimney 21 through a pipe and an induced draft fan 20 for discharge to the atmosphere;

[0090] The inlet end of the washing tower 17 is connected to the top of the overflow pipe 12 of the cyclone heat exchanger 1 or the tail gas outlet 82 of the second heat exchanger 8 through a pipeline; the lower part of the washing tower 17 is provided with a liquid storage tank 171 for storing alkali solution, and the outlet end of the liquid storage tank 171 is connected to the deliquescence tower 19;

[0091] The outlet of the alkali liquid tank 8 is connected to the nozzle 16 through a pipeline and a circulation pump 9. The nozzle 16 is arranged in the upper middle part of the washing tower 17.

[0092] Furthermore, a steam grinding device 500 is provided, which includes a steam turbine 22 and a grinding device 23; the inlet of the steam turbine 22 is connected to the steam outlet 614 of the first heat exchanger 6 and the steam outlet 822 of the second heat exchanger 8 through a pipeline; the conveying device 7 for conveying the slag particles below the discharge port 612 of the drum 61 of the first heat exchanger 6 is connected to the feed port of the grinding device 500, and the discharge port of the grinding device 500 is delivered to the user.

[0093] Preferably, an air cushion 114 and a water cushion 115 are provided in the feed channel 111 of the cylinder 11 of the cyclone heat exchanger 1, and the inlets of the air cushion and the water cushion are connected to compressed air and water, respectively; preferably, the air cushion and the water cushion are narrow grooves that are provided in the 1 / 4 arc of the circumferential tangential inlet from the upper part of the side wall of the cylinder 11 of the cyclone heat exchanger 1 and are connected to the cylinder 11, and the inlets of the air cushion and the water cushion are connected to compressed air and water, respectively.

[0094] Preferably, the side walls of the cylinder 11 of the cyclone heat exchanger 1 are respectively an insulating wear-resistant lining, a water-cooled wall, and a steel plate from the inside to the outside; the insulating wear-resistant lining is preferably made of silicon carbide material; preferably, the water-cooled wall is provided with a water-cooled wall cold water inlet 116 connected to the deaeration water pipeline, and the water-cooled wall hot water outlet 117 is connected to the inlet end of the steam drum 2.

[0095] Preferably, the upper part of the barrel 11 of the cyclone heat exchanger 1 is a cylindrical barrel, and the lower part is an inverted conical barrel; preferably, the angle between the generatrix of the inverted conical barrel and the horizontal plane is 20-80°, preferably 20-60°, or more preferably 20-40°.

[0096] Preferably, the overflow pipe 12 is a circular tube of equal diameter or a tube with an upper diameter 1 to 2 times the lower diameter and an enlarged upper portion.

[0097] Example

[0098] After blast furnace 600 molten slag flows freely into the shroud through a 600mm x 600mm slag inlet at the top of the shroud. The slag stream maintains a relatively stable flow rate, rated at 5 tons / minute. Compressed air and water are mixed in an ejector and then ejected as a high-pressure jet. The air atomizes the water into droplets with a diameter of 50 to 500 μm. The high-pressure jet from the ejector cuts the slag stream into droplets with a diameter of 1 to 5 mm, exchanging heat with the air and droplets. The droplets completely vaporize into water vapor, while the air absorbs the heat and becomes high-temperature gas. The droplets cool and solidify into solid slag particles, which travel forward with the gas flow inside the shroud into the cyclone heat exchanger. A water cushion (10 mm wide and 1000 mm long) is installed on the inlet tube wall of the cyclone heat exchanger. Compressed air and fresh water, respectively, are introduced to sweep away slag particles, preventing them from adhering to the wall and impacting the normal operation of the cyclone heat exchanger. High-temperature slag particles and high-temperature gas are quickly separated under the action of the cyclone field. The slag particles migrate to the side wall under the action of gravity and centrifugal force and are discharged from the (star-shaped) discharge valve at the bottom of the cyclone heat exchanger.

[0099] The high-temperature, dust-laden gas is discharged from the overflow pipe at the top of the cyclone heat exchanger. During its flow, it exchanges heat with the cooling medium within the spiral tube bundle, thereby recovering the heat from the high-temperature gas. The cooling medium within the spiral tube bundle is deoxygenated water, which is first transferred to the steam drum for preheating and then pumped into the spiral tube bundle via a hot water pump. The deoxygenated water is evenly distributed to each spiral tube through the bundle's water inlet. After exchanging heat with the high-temperature gas, the deoxygenated water vaporizes into superheated steam at 230°C, 1.2 MPA(G), and 9 t / h. This steam is then collected at the bundle outlet at the end of the spiral tube bundle and enters the steam drum for gas-liquid separation. The separated steam is then transferred to the steam turbine.

[0100] The inner wall of the cyclone heat exchanger is lined with silicon carbide (or CoCrAlTaY) and the outer wall is equipped with a water-cooled wall. Deoxygenated water enters through the cold water inlet of the water-cooled wall, exchanges heat with the high-temperature materials in the cyclone heat exchanger, and is then transported from the hot water outlet of the water-cooled wall to the steam drum for further heat exchange.

[0101] After exiting the overflow pipe, the hot, dusty gas flows into the second heat exchanger, where it exchanges heat with the heat exchanger tubes. Deoxygenated water is introduced into the second heat exchanger. The deoxygenated water exchanges heat with the hot, dusty gas outside the tubes, vaporizing it into superheated steam at 250°C, 1.6 MPA, and 9 t / h. The resulting steam is then fed into the steam turbine. The dusty gas, after heat exchange, is then purified and discharged through the desulfurization and dust removal unit. The slag particles, after heat exchange, are discharged through the star-shaped discharge valve at the bottom of the cyclone heat exchanger and enter the drum of the first heat exchanger for further heat exchange. The heat exchange tube bundle is housed within the drum, which is filled with deoxygenated water. A motor drives the shaft to maintain a constant rotation speed. The deoxygenated water within the heat exchanger tube bundle exchanges heat with the hot, dusty gas outside the tubes, absorbing heat and rapidly vaporizing it into superheated steam at 250°C, 1.6 MPA, and 9 t / h. The resulting superheated steam is then fed into the steam turbine. The cooled slag particles fall through the slag discharge port at the bottom of the drum onto a conveyor for further utilization in the steam grinding unit.

[0102] Since SO2 acid gas is easily generated during the granulation process, the dust-laden gas discharged from the first heat exchanger enters the scrubbing tower for desulfurization and dust removal. An alkaline solution (such as NaOH solution) is used as an absorbent and stored in an alkali tank. The alkali solution is transported to the nozzle through a circulating pump. After the alkali solution is sprayed out through the nozzle, it reacts with SO2 in the gas to generate Na2SO3. The purified gas and excess alkali solution flow into the liquid storage tank at the bottom of the scrubbing tower. The gas enters the deliquidation tower from the interface at the top of the liquid storage tank, and the liquid foam mixed in the gas is removed under the action of the deliquidator. The excess alkali solution enters the deliquidation tower from the interface at the bottom of the liquid storage tank and is discharged from the liquid outlet and re-enters the circulation pump. After desulfurization and dust removal, the gas temperature is ≤80℃ and the SO2 concentration is ≤50mg / m 3 , particle concentration ≤10mg / m 3 , drawn out by the induced draft fan and discharged through the chimney in compliance with the standards.

[0103] The low-temperature slag particles discharged from the drum fall onto a conveyor and are transported to the grinding unit. The superheated steam generated by the cyclone heat exchanger and waste heat recovery unit converges and enters the steam turbine, where it converts the steam's thermal energy into kinetic energy, driving the grinding unit. The slag particles are ground into a powder with a particle size of approximately 50 μm, which is used as the primary raw material for cement and fertilizer production.

[0104] The above are only preferred embodiments of the present invention and are not intended to limit the scope of protection of the invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A liquid blast furnace slag granulation and waste heat recovery system, characterized in that: It includes a cyclone heat exchange device, a granulation device, and a waste heat recovery device; wherein, The cyclone heat exchange device comprises: Cyclone heat exchanger, comprising: The cylinder has a feed port and a feed channel on one side of its upper part, and a conical lower part with a slag discharge port and a discharge valve at its bottom; The overflow pipe has its lower part vertically inserted into the upper part of the cylinder; the top of the overflow pipe is provided with a high-temperature dust-laden gas outlet; The spiral tube bundle is arranged in the overflow pipe, and the two ends of the spiral tube bundle, namely the tube bundle water inlet and the tube bundle air outlet, are located outside the overflow pipe; The steam drum has an inlet connected to the deaerated water pipeline, a deaerated water outlet connected to the water inlet of the spiral tube bundle through a pipeline and a hot water pump, and a gas outlet connected to the steam drum; the steam outlet on the steam drum is connected to the steam pipe network; The granulation device includes an ejector and a flow guide cover; the ejector outlet corresponds to the flow guide cover inlet, and the flow guide cover outlet is connected to the cyclone heat exchanger feed channel of the cyclone heat exchange device; the top surface of the flow guide cover is provided with a slag inlet; The ejector includes an ejector provided with a compressed air interface and a water interface, the compressed air interface and the water interface are connected to a compressed air pipe and a water pipe respectively; the ejector outlet is connected to the guide cover inlet; the ejector is a Venturi ejector; The waste heat recovery device is arranged below the cyclone heat exchange device and includes: The first heat exchanger is a drum-type heat exchanger, comprising a drum and a drive motor; a feed port and a discharge port are provided at each end of the drum, the feed port being connected to the slag discharge port of the cyclone heat exchanger cylinder; a water inlet connected to the deaerated water pipeline is provided at one end of the drum provided with the feed port, and a steam outlet is provided at the other opposite end; a heat exchange tube bundle is provided within the drum, the inlet of the heat exchange tube bundle being connected to the deaerated water pipeline, and the outlet of the heat exchange tube bundle, i.e., the steam outlet, being connected to the steam pipe network; a conveyor device for conveying slag particles is provided below the drum discharge port; the conveyor device is a belt conveyor; The second heat exchanger includes a cylindrical body, with an exhaust gas inlet and an exhaust gas outlet at both ends respectively; the exhaust gas inlet is connected to the high-temperature dust-containing gas outlet at the top of the overflow pipe through a pipeline; a heat exchange tube is arranged in the second heat exchanger, and the two ends of the heat exchange tube are a water inlet and a steam outlet, the water inlet is connected to the deoxygenated water pipeline, and the steam outlet is connected to the steam pipeline network or the user; the heat exchange tube adopts a serpentine structure.

2. The liquid blast furnace slag granulation and waste heat recovery system according to claim 1, characterized in that: A desulfurization and dust removal device is also provided, which includes an alkali liquid tank, a circulation pump, a nozzle, a washing tower, a liquid storage tank, a liquid removal tower, an induced draft fan, and a chimney; A deliquidation tower, wherein a deliquidator is provided in the middle or upper part thereof; a liquid outlet is provided at the lower part of the deliquidation tower and is connected to the inlet pipe of the circulation pump; a gas outlet is provided at the top of the deliquidation tower and is connected to a chimney through a pipe and an induced draft fan for discharge to the atmosphere; The inlet end of the washing tower is connected to the top of the overflow pipe of the cyclone heat exchanger or the tail gas outlet of the second heat exchanger through a pipeline; the lower part of the washing tower is provided with a liquid storage tank for storing alkali solution, and the outlet end of the liquid storage tank is connected to the deliquescence tower; The outlet end of the alkali liquid tank is connected to the nozzle through a pipeline and a circulation pump. The nozzle is arranged in the upper middle part of the washing tower.

3. The liquid blast furnace slag granulation and waste heat recovery system according to claim 1 or 2, characterized in that: A steam grinding device is also provided, which includes a steam turbine and a grinding device; the inlet of the steam turbine is connected to the steam outlet of the first heat exchanger and the steam outlet of the second heat exchanger through a pipeline; the conveying device for transporting the slag particles below the discharge port of the first heat exchanger drum is connected to the feed port of the grinding device, and the discharge port of the grinding device is transported to the user.

4. The liquid blast furnace slag granulation and waste heat recovery system according to claim 1 or 2, characterized in that: An air cushion and a water cushion are provided in the feed channel of the cylinder of the cyclone heat exchanger, and the inlets of the air cushion and the water cushion are connected to compressed air and water respectively; the air cushion and the water cushion are respectively narrow grooves that are provided in the 1 / 4 arc of the circumferential tangential inlet from the upper part of the side wall of the cylinder of the cyclone heat exchanger and pass through the cylinder, and the inlets of the air cushion and the water cushion are connected to compressed air and water respectively.

5. The liquid blast furnace slag granulation and waste heat recovery system according to claim 3, characterized in that: An air cushion and a water cushion are provided in the feed channel of the cylinder of the cyclone heat exchanger, and the inlets of the air cushion and the water cushion are connected to compressed air and water respectively; the air cushion and the water cushion are respectively narrow grooves that are provided in the 1 / 4 arc of the circumferential tangential inlet from the upper part of the side wall of the cylinder of the cyclone heat exchanger and pass through the cylinder, and the inlets of the air cushion and the water cushion are connected to compressed air and water respectively.

6. The liquid blast furnace slag granulation and waste heat recovery system according to claim 1 or 2, characterized in that: The side walls of the cylinder of the cyclone heat exchanger are respectively composed of an insulating and wear-resistant lining, a water-cooled wall, and a steel plate from the inside to the outside; the insulating and wear-resistant lining is made of silicon carbide material; the water-cooled wall is provided with a water-cooled wall cold water inlet connected to the deaerated water pipeline, and the water-cooled wall hot water outlet is connected to the steam drum inlet.

7. The liquid blast furnace slag granulation and waste heat recovery system according to claim 3, characterized in that: The side walls of the cylinder of the cyclone heat exchanger are respectively composed of an insulating and wear-resistant lining, a water-cooled wall, and a steel plate from the inside to the outside; the insulating and wear-resistant lining is made of silicon carbide material; the water-cooled wall is provided with a water-cooled wall cold water inlet connected to the deaerated water pipeline, and the water-cooled wall hot water outlet is connected to the steam drum inlet.

8. The liquid blast furnace slag granulation and waste heat recovery system according to claim 4, characterized in that: The side walls of the cylinder of the cyclone heat exchanger are respectively composed of an insulating and wear-resistant lining, a water-cooled wall, and a steel plate from the inside to the outside; the insulating and wear-resistant lining is made of silicon carbide material; the water-cooled wall is provided with a water-cooled wall cold water inlet connected to the deaerated water pipeline, and the water-cooled wall hot water outlet is connected to the steam drum inlet.

9. The liquid blast furnace slag granulation and waste heat recovery system according to claim 5, characterized in that: The side walls of the cylinder of the cyclone heat exchanger are respectively composed of an insulating and wear-resistant lining, a water-cooled wall, and a steel plate from the inside to the outside; the insulating and wear-resistant lining is made of silicon carbide material; the water-cooled wall is provided with a water-cooled wall cold water inlet connected to the deaerated water pipeline, and the water-cooled wall hot water outlet is connected to the steam drum inlet.

10. The liquid blast furnace slag granulation and waste heat recovery system according to claim 1 or 2, characterized in that: The upper part of the cylinder of the cyclone heat exchanger is a cylindrical cylinder, and the lower part is an inverted conical cylinder; the angle between the generatrix of the inverted conical cylinder and the horizontal plane is 20-80 degrees.

11. The liquid blast furnace slag granulation and waste heat recovery system according to claim 3, characterized in that: The upper part of the cylinder of the cyclone heat exchanger is a cylindrical cylinder, and the lower part is an inverted conical cylinder; the angle between the generatrix of the inverted conical cylinder and the horizontal plane is 20-80 degrees.

12. The liquid blast furnace slag granulation and waste heat recovery system according to claim 4, characterized in that: The upper part of the cylinder of the cyclone heat exchanger is a cylindrical cylinder, and the lower part is an inverted conical cylinder; the angle between the generatrix of the inverted conical cylinder and the horizontal plane is 20-80 degrees.

13. The liquid blast furnace slag granulation and waste heat recovery system according to claim 5, characterized in that: The upper part of the cylinder of the cyclone heat exchanger is a cylindrical cylinder, and the lower part is an inverted conical cylinder; the angle between the generatrix of the inverted conical cylinder and the horizontal plane is 20-80 degrees.

14. The liquid blast furnace slag granulation and waste heat recovery system according to claim 6, characterized in that: The upper part of the cylinder of the cyclone heat exchanger is a cylindrical cylinder, and the lower part is an inverted conical cylinder; the angle between the generatrix of the inverted conical cylinder and the horizontal plane is 20-80 degrees.

15. The liquid blast furnace slag granulation and waste heat recovery system according to claim 7, characterized in that: The upper part of the cylinder of the cyclone heat exchanger is a cylindrical cylinder, and the lower part is an inverted conical cylinder; the angle between the generatrix of the inverted conical cylinder and the horizontal plane is 20-80 degrees.

16. The liquid blast furnace slag granulation and waste heat recovery system according to claim 8, characterized in that: The upper part of the cylinder of the cyclone heat exchanger is a cylindrical cylinder, and the lower part is an inverted conical cylinder; the angle between the generatrix of the inverted conical cylinder and the horizontal plane is 20-80 degrees.

17. The liquid blast furnace slag granulation and waste heat recovery system according to claim 9, characterized in that: The upper part of the cylinder of the cyclone heat exchanger is a cylindrical cylinder, and the lower part is an inverted conical cylinder; the angle between the generatrix of the inverted conical cylinder and the horizontal plane is 20-80 degrees.

18. The liquid blast furnace slag granulation and waste heat recovery system according to claim 10, characterized in that: The included angle between the generatrix of the inverted cone cylinder and the horizontal plane is 20~60°.

19. The liquid blast furnace slag granulation and waste heat recovery system according to claim 11, characterized in that: The included angle between the generatrix of the inverted cone cylinder and the horizontal plane is 20~60°.

20. The liquid blast furnace slag granulation and waste heat recovery system according to claim 12, characterized in that: The included angle between the generatrix of the inverted cone cylinder and the horizontal plane is 20~60°.

21. The liquid blast furnace slag granulation and waste heat recovery system according to claim 13, characterized in that: The included angle between the generatrix of the inverted cone cylinder and the horizontal plane is 20~60°.

22. The liquid blast furnace slag granulation and waste heat recovery system according to claim 14, characterized in that: The included angle between the generatrix of the inverted cone cylinder and the horizontal plane is 20~60°.

23. The liquid blast furnace slag granulation and waste heat recovery system according to claim 15, characterized in that: The included angle between the generatrix of the inverted cone cylinder and the horizontal plane is 20~60°.

24. The liquid blast furnace slag granulation and waste heat recovery system according to claim 16, characterized in that: The included angle between the generatrix of the inverted cone cylinder and the horizontal plane is 20~60°.

25. The liquid blast furnace slag granulation and waste heat recovery system according to claim 17, characterized in that: The included angle between the generatrix of the inverted cone cylinder and the horizontal plane is 20~60°.

26. The liquid blast furnace slag granulation and waste heat recovery system according to claim 10, characterized in that: The included angle between the generatrix of the inverted cone cylinder and the horizontal plane is 20~40°.

27. The liquid blast furnace slag granulation and waste heat recovery system according to claim 11, characterized in that: The included angle between the generatrix of the inverted cone cylinder and the horizontal plane is 20~40°.

28. The liquid blast furnace slag granulation and waste heat recovery system according to claim 12, characterized in that: The included angle between the generatrix of the inverted cone cylinder and the horizontal plane is 20~40°.

29. The liquid blast furnace slag granulation and waste heat recovery system according to claim 13, characterized in that: The included angle between the generatrix of the inverted cone cylinder and the horizontal plane is 20~40°.

30. The liquid blast furnace slag granulation and waste heat recovery system according to claim 14, characterized in that: The included angle between the generatrix of the inverted cone cylinder and the horizontal plane is 20~40°.

31. The liquid blast furnace slag granulation and waste heat recovery system according to claim 15, characterized in that: The included angle between the generatrix of the inverted cone cylinder and the horizontal plane is 20~40°.

32. The liquid blast furnace slag granulation and waste heat recovery system according to claim 16, characterized in that: The included angle between the generatrix of the inverted cone cylinder and the horizontal plane is 20~40°.

33. The liquid blast furnace slag granulation and waste heat recovery system according to claim 17, characterized in that: The included angle between the generatrix of the inverted cone cylinder and the horizontal plane is 20~40°.

34. The liquid blast furnace slag granulation and waste heat recovery system according to claim 1, characterized in that: The overflow pipe is a circular pipe of equal diameter or a pipe body with an upper diameter 1 to 2 times the lower diameter.

35. The liquid blast furnace slag granulation and waste heat recovery system according to claim 1, characterized in that: The discharge valve is a star-shaped discharge valve.

36. A method for using the liquid blast furnace slag granulation and waste heat recovery system according to claim 1, characterized in that: Compressed air and water enter the ejector cavity through the gas and water interfaces on the granulation device respectively, and mix to form a high-speed jet that enters the guide cover, shearing the molten blast furnace slag that freely falls from the slag pot into the guide cover. The molten blast furnace slag is broken and solidified into solid particles under the shear and impact of the high-speed jet; the granulated blast furnace slag enters the cyclone heat exchanger along with the high-temperature air and water vapor, and is quickly separated in the cyclone heat exchanger by taking advantage of the large density difference between the gas and solid phases; the deoxygenated water is pressurized by the hot water pump and transported to the spiral tube, where it exchanges heat with the high-temperature gas outside the tube to obtain saturated or superheated steam, which is then transported to the second heat exchanger of the waste heat recovery device; after separation from the gas The high-temperature slag enters the first heat exchanger of the waste heat recovery device through the discharge valve. Cooling water is introduced into the heat exchange tube bundle in the drum of the first heat exchanger. The liquid water quickly absorbs the heat of the high-temperature slag in the drum and converts it into water vapor. The temperature of the high-temperature slag is further reduced to below 100°C. The low-temperature slag particles flow out from the bottom of the waste heat recovery device and are transported by the conveyor for recycling. The low-temperature blast furnace slag particles are transported by the conveyor to the steam grinding device. The saturated or superheated water vapor generated by the first heat exchanger and the second heat exchanger enters the steam turbine. The thermal energy is converted into kinetic energy, which drives the grinding device to grind the blast furnace slag particles after heat exchange into powder as the main raw material for cement production.

37. The method of liquid blast furnace slag granulation and waste heat recovery system according to claim 36, characterized in that: The gas after heat exchange enters the desulfurization and dust removal device, and the alkali liquid in the alkali liquid tank is sprayed into the air flow from bottom to top through the nozzle through the circulation pump, achieving a high-efficiency washing and purification effect; the mixed gas after washing is separated into gas and liquid, and the liquid re-enters the liquid storage tank and is recycled. The purified gas is discharged after the demister removes the entrained liquid.

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