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, a waste heat recovery device and a steam power generation device. Compressed air and water are mixed in the granulation device injector cavity to form a high-speed jet, which shears the molten blast furnace slag from the flow guide cover, and the molten slag is broken and solidified into solid particles; the granulated blast furnace slag enters the cyclone heat exchanger with high-temperature air and water vapor to achieve rapid separation, the deoxygenated water is transported into the spiral pipe bundle and exchanges heat with the high-temperature gas outside the pipe to obtain saturated or superheated steam, which is transported to the second heat exchanger of the waste heat recovery device; the high-temperature slag separated from the gas enters the first heat exchanger of the waste heat recovery device, and the cooling water flowing therein rapidly absorbs the heat of the high-temperature slag to change into water vapor; the saturated or superheated water vapor generated by the steam drum, the first and second heat exchangers of the cyclone heat exchange device enters the steam turbine to drive the power generation device, and finally the thermal energy is converted into electric energy which is supplied to users through the power transmission and distribution device.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of metallurgical molten slag granulation and waste heat recovery, and particularly relates to a liquid blast furnace slag granulation and waste heat recovery system and method. BACKGROUND

[0002] Blast furnace slag is a solid waste produced in the process of steel smelting, and its main components include CaO, MgO, AL2O3, MnO, etc. The blast furnace slag has a temperature of 1400-1600℃, and each ton of blast furnace slag carries about 1770MJ of heat energy, equivalent to 60kg of standard coal, and has great heat recovery potential. In 2020, the pig iron output in China was 888 million tons, and according to a slag-iron ratio of 400kg / t, the blast furnace slag output was about 355 million tons; according to the estimation of 1770MJ carried by each ton of blast furnace slag, the sensible heat of these blast furnace slags was about 6.28x1012 8 GJ, equivalent to 21.42 million tons of standard coal. In addition, after accumulation in recent years, the current stockpiling amount of blast furnace slag in China is about more than 1 billion tons, which not only occupies enterprise land, but also pollutes the environment and harms the health of organisms and human bodies.

[0003] To realize the resource utilization of blast furnace slag, the most common method for treating blast furnace slag in China at present is water granulation. Ren Yubin et al. adopted a water granulation process of granulation tower + dehydrator + steam centralized discharge, and the molten slag was rapidly water-quenched and granulated by the pressure water flow of the granulation system; the slag-water mixture generated was fully buffered and water-quenched after entering the granulation tower, and then flowed into the screen of the dehydrating device through the water slag channel to enter the dehydration program; the high-temperature steam generated in the granulation process was discharged at a high altitude through the chimney on the upper part of the gas collecting device (Ren Yubin. Design of water granulation system of Shougang Changgang 9# blast furnace [J]. Jiangxi Building Materials, 2021, 04: 238-24). Although the glassy blast furnace slag generated by this method can be applied to the cement industry for resource utilization, the overall treatment system has a large water consumption, and 3t of granulation water is needed for treating 1 ton of molten slag, the water consumption per ton of slag is 0.7t, the power consumption per ton of slag is 3kW·h, and a large amount of waste steam rich in H2S and SO2 pollutants is discharged, and the waste heat recovery efficiency of the flue gas in this process is 0. In the subsequent resource utilization, the water in the water slag also needs to be dried, and 1 ton of slag needs to consume 1200m 3 of 500℃ hot air (Li Yongqian. Blast furnace molten slag granulation heat exchange device based on multi-medium coupling [P]. China: CN 112146446 A, 2020.12.29.), and the power consumption is about 0.1kW·h / ton of slag. Therefore, the blast furnace slag granulation and waste heat recovery system should meet the following requirements: 1) a reasonable granulation process to solve the problems of large water consumption and serious pollution; 2) a reasonable waste heat recovery system to solve the problem of low waste heat recovery efficiency; 3) a small overall land occupation, compact equipment, stable operation, and convenient maintenance.

[0004] To solve the problem of large water consumption and reduce the generation of harmful gases, dry granulation can be used. Zou Youwu et al. introduced the blast furnace slag sensible heat comprehensive recovery technology jointly developed by Kawasaki Steel and other six companies in Japan. The molten slag enters the wind tunnel from the chute and is blown and broken into particles by the granulation wind. The cooling circulating wind is blown into the wind tunnel to cool the slag particles to 800℃ and discharge them from the wind tunnel. After the granulated slag is screened by a hot screen to remove large particles, it is stored in a high-temperature hopper, and then undergoes secondary heat exchange in multiple flow layers to further cool the granulated slag to about 150℃(Zou Youwu. Blast furnace slag sensible heat comprehensive recovery technology developed in Japan[J]. Anshan Technology, 1990, 10: 3-14). The air granulation required for the equipment with a processing capacity of 100t / h high-temperature molten slag is 4000m 3 / min, the circulating cooling air volume is 3100m 3 / min(186000m 3 / h), and the wind pressure is calculated as 0.2MPa. The power of the fan is calculated to be about 40kW·h / ton of slag(Chen Xukui. Fan Handbook[M]. Beijing: Mechanical Industry Press, 2011: 21-22). In this process, the following problems exist: 1) The air consumption is huge, which is 190000m 3 / h, and the power consumption is about 40kW·h / ton of slag, which is about 13 times that of the water granulation method. 2) The granulation, heat exchange and gas-solid separation devices in the system occupy a large area. First, the main size of the wind tunnel used for granulation and primary heat exchange is: length 25m, width 7m, height 13m; second, the cyclone dust collector in the system is used to separate and remove dust from 190000m 3 / h of gas, and the average velocity of the cyclone dust collector cylinder net section is 2.5m / s, so the diameter of the cyclone dust collector cylinder is about 5200mm(Zhang Dianyin. Dust Collector Handbook[M]. Beijing: Chemical Industry Press, 2014: 114). 3) When the slag flow changes, the wind speed and volume are not easy to coordinate, and a large amount of cold air entering the system also reduces the recovery efficiency.

[0005] The blast furnace slag air granulation and waste heat recovery technology are developed from the air granulation process jointly developed by Kawasaki Steel and other six companies in Japan; subsequent improvement patents such as US patents US 20170297113A1 and US20170137912A1 of HATCH company, and US patents US6,803,016B2 and US2002 / 0117786A1 invented by Alfred Edlinger et al.

[0006] A centrifugal molten slag dry granulation and waste heat recovery power generation system is disclosed in Chinese utility model patent CN202530095U. The system includes a slag receiving device, a slag centrifugal rapid cooling granulation device, a slag slow cooling device, a waste heat recovery power generation device, and a waste gas purification treatment device. The unique centrifugal granulation device is used to rapidly cool the molten slag to a glassy state and further slowly cool and heat exchange on a water-cooled vibrating rake bed, and then generate steam in a waste heat boiler to drive a steam turbine generator set to generate power. According to the data provided in the patent, under the action of the rotating cup centrifugal force, the blast furnace slag becomes droplets and exchanges heat with the cooling air input by the air blower. 1) If the initial temperature of the blast furnace slag is 1500°C and the mass flow rate is 2t / min, the air absorbs heat from 25°C to 850°C. According to the heat balance principle, the cooling air volume is about 103122m 3 / h, the air pressure is calculated as 0.2MPa, and the power of the fan is about 18kW·h / ton of slag; 2) When the rotating cup speed is 3000r / min and the molten slag flow rate is 2t / min, the required motor power is 0.1-0.125kW·h / ton of slag (Sun Peng. Status and prospect of blast furnace slag comprehensive utilization [J]. Anshan technology, 2008, 3: 6-9). The power consumption in the blast furnace slag granulation process is about 18.1kW·h / ton of slag, which is about 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 rapid cooling granulation device in the system occupies a large area, and the diameter of the slag centrifugal rapid cooling granulation device for processing 40t / h of slag is 4.2m. If 100t / h of molten slag is processed, three slag centrifugal rapid cooling granulation devices with a diameter of 4.2m are needed in parallel (Li Shun. Domestic and foreign methods of recovering sensible heat from molten blast furnace slag [J]. Industrial heating, 2009, 38(03): 1-4). At the same time, the rotating cup in high speed rotation directly contacts with high temperature molten slag, which reduces the reliability of the operation of the granulation equipment. In addition, the granulation quality is unstable and slag wool is easily formed during rotation, and the effect of adjusting the rotating speed is not ideal. High temperature molten slag concentrated high speed impact on a certain part of the equipment also easily causes local overheating of the equipment and damages the equipment. At present, the dry granulation method is still in the experimental research stage and has not been industrialized (Liu Meng. Status and trend of blast furnace slag treatment technology [J]. Metallurgical equipment, 2021, 266: 1-4).

[0007] Chinese invention patent CN108060279A discloses a method combining dry granulation and water quenching granulation. The motor drives the granulation cup to rotate, so that the molten slag entering the cup is thrown out to form small droplets. The small droplets are cooled by the cooling water sprayed by the water sprayer to form slag particles. The slag particles fall through the discharge port onto the conveyor and are sent out. The cooling water not gasified during the granulation process flows back to the water collection tank, and the gasified water vapor enters the water vapor waste heat recovery system, so that the heat is utilized. The invention still uses centrifugal method as the initial granulation method. The high-temperature molten slag directly erodes the surface of the granulation cup, which can cause the rotating cup to be easily burned and deformed, and cannot be stably operated for a long time. Moreover, the acidic gases such as SO2 and H2S generated by water quenching enter the waste heat recovery system without being treated, which can cause the waste heat recovery equipment to be severely corroded after long-term operation, and brings hidden dangers to safety production.

[0008] Chinese invention patent CN101550460A discloses a method and device for rapid cooling and waste heat recovery of blast furnace slag. The device carries the blast furnace slag into the cyclone separator through fluidization wind to realize gas-solid separation, and at the same time, the blast furnace slag is rapidly cooled by the double cooling system of fluidization wind and water-cooled wall around the gas-solid separator to achieve the effect of rapid cooling. The separated blast furnace slag enters the storage tank, and fluidization wind is introduced at the bottom of the storage tank to make it in a bubbling bed state for further cooling. The air and cooling water are pressurized and then enter the boiler to realize waste heat recovery. From the granulation method, this method belongs to the typical air quenching granulation process. However, because the density of air is small and the impact force is small, the air volume and air pressure required for granulating molten slag are very large. The total air consumption in this process is 5000m 3The power of the fan is about 12 kW h / ton of slag, calculated according to the outlet air pressure of 0.2 MPa. From the structure, the invention mainly utilizes fluidized air and water-cooled wall to achieve the rapid cooling of blast furnace slag. Due to the low thermal conductivity of air, the efficiency of the inter-wall heat exchange is much lower than that of the direct contact type. The high-temperature slag droplets formed by air blowing adhere directly to the water-cooled wall, reducing the heat exchange effect, leading to a gradual decrease in the glass body conversion rate of blast furnace slag, and affecting the safe operation of the system and the resource utilization of blast furnace slag. In addition, the spin-in vortex core phenomenon exists in the whole space of the gas-solid separator, and there is also an eccentric longitudinal circulation near the dust outlet at the lower part of the separator. These conditions can cause the particles separated to the wall to be accidentally entrained into the upward inner vortex, thereby causing particle backmixing (Wang Lu. Influence of inlet structure and gas velocity on non-steady state characteristics of inner vortex in cyclone separator [D]. Taiyuan University of Technology, 2018). The direct connection between the storage tank and the gas-solid separator in the structure of the invention can easily lead to the return of the separated blast furnace slag carried by the fluidizing air into the gas-solid separator, reducing the gas-solid separation efficiency. In addition, the fluidizing air can carry a large amount of small-diameter particles into the waste heat boiler. If the boiler has a large amount of accumulated soot, it not only affects the heat exchange efficiency of the boiler and reduces the steam output, but also threatens the long-term safe operation of the boiler (Wang Guozhen. Reducing soot adhesion to improve waste heat boiler heat exchange efficiency [J]. Copper Industry Engineering, 2021, 03: 31-33). From the aspect of waste heat recovery, air is a poor conductor of heat, with a thermal conductivity of only 0.023 W / m·k, which is much smaller than the thermal conductivity of water (0.59 W / m·K). In the invention, air is used as the cooling medium, and the temperature of the hot air obtained by heat exchange with molten slag is only 300℃, resulting in low waste heat recovery efficiency.

[0009] In addition, there are also various ways to recover the heat of high-temperature flue gas formed during the molten slag cooling process. Chinese invention patent CN1212870632U discloses a flue gas waste heat recovery system. The cooling medium flows into the heat exchange structure from the inlet, absorbs the heat energy generated at the cylinder wall and / or tube wall of the cylinder by the water-cooled wall and the wrapped tube heat exchange structure, and flows out from the outlet. The cooling medium can be reused in various ways, thereby realizing the recovery and utilization of waste heat. From the structure, the gas with dust enters the separator along the inlet pipe of the cyclone separator, and the solid particles in the gas directly impact the outer wall of the tube inserted into the cyclone separator cavity. Under long-term operation, the heat exchange tube wrapped around the outer wall of the tube is prone to cracking, which can cause leakage of the cooling medium and affect the safe operation of the system. From the aspect of waste heat recovery, the wrapped tube is only distributed on the tube wall, and the space inside the tube is not fully utilized, resulting in limited heat exchange area and direct emission of most of the heat in the flue gas, causing waste of resources.

[0010] Xu et al. proposed a casing heat exchange type cyclone dust collector, heat pipe bundle inserted into the cyclone dust collector, dust-containing flue gas purification through the heat pipe heat exchange to achieve the purpose of heat exchange and dust removal (Xu. Numerical simulation of high-efficiency heat pipe heat exchange type cyclone dust collector [J]. Industrial furnace, 2013, 35(01): 9-12). The paper analyzes the distribution of the cyclone field, separation efficiency and pressure drop under the conditions of inlet Reynolds number, cyclone structure size and pipe bundle structure size, and does not systematically analyze the influence of different inlet Reynolds numbers and cyclone structure sizes on the flow field distribution, separation efficiency and pressure drop in the cyclone separator. The structure parameters of the cyclone separator, different inlet Reynolds numbers and pipe bundle structure parameters are not related to the heat exchange effect of the pipe bundle. The structure makes the classification and dust removal efficiency of solid particles with particle size of 5-13 um increase to a certain extent, but the article lacks experimental verification of the structure for effective recovery of flue gas heat. In addition, from the structure, the straight pipe heat exchange is used in the structure, and compared with the spiral pipe or coil in the same pipe diameter and space, the heat exchange area of the straight pipe is much smaller. SUMMARY

[0011] The purpose of the present application is to provide a liquid blast furnace slag granulation and waste heat recovery system and method, which solves the problems of large water consumption, serious pollution, low waste heat recovery efficiency and large system area in the prior art, and has the advantages of low energy consumption, small pollution, granulation function, rapid and efficient gas-solid separation and waste heat recovery function.

[0012] To achieve the above purpose, the technical scheme of the present application is:

[0013] A liquid blast furnace slag granulation and waste heat recovery system, comprising a cyclone heat exchange device, a granulation device, a waste heat recovery device and a steam power generation device; wherein,

[0014] The cyclone heat exchange device comprises:

[0015] The cyclone heat exchange device comprises:

[0016] The cylinder has a feed inlet and a feed passage on one side of the upper part, and the lower part is conical, and the bottom is provided with a slag discharge port and a discharge valve; preferably, the discharge valve is a star-shaped discharge valve;

[0017] The overflow pipe is vertically inserted into the upper part of the cylinder; the top end of the overflow pipe is provided with a high-temperature dust-containing gas outlet;

[0018] The spiral pipe bundle is arranged in the overflow pipe, and the two ends of the spiral pipe bundle, i.e. the pipe bundle water inlet and the pipe bundle gas outlet, are located outside the overflow pipe;

[0019] A steam drum, an inlet end of which is connected to a deoxygenated water pipeline, the steam drum is provided with a deoxygenated water outlet and is connected to a tube bundle inlet of the spiral tube bundle through a pipeline and a hot water pump, a tube bundle gas outlet of the spiral tube bundle is connected to the steam drum; a steam outlet on the steam drum is connected to a steam pipeline network;

[0020] The granulating device comprises an injector and a flow guide cover; the injector outlet corresponds to the flow guide cover inlet, and the flow guide cover outlet is connected to the cyclone heat exchanger inlet channel of the cyclone heat exchange device; the top surface of the flow guide cover is provided with a molten slag inlet;

[0021] The injector comprises an injector provided with a compressed air interface and a water interface, the compressed air interface and the water interface are respectively connected to a compressed air pipe and a water pipe; the injector outlet is connected to the flow guide cover inlet; preferably, the injector is a Venturi injector;

[0022] The waste heat recovery device is arranged below the cyclone heat exchange device and comprises:

[0023] The first heat exchanger is a drum-type heat exchanger comprising a drum and a driving motor; the drum is provided with an inlet and an outlet at two ends respectively, the inlet is connected to the slag outlet of the cyclone heat exchanger cylinder, the drum end provided with the inlet is further provided with a water inlet connected to the deoxygenated water pipeline, and the opposite end is provided with a steam outlet; the drum is provided with a heat exchange tube bundle, the heat exchange tube bundle inlet is connected to the deoxygenated water pipeline, and the heat exchange tube bundle outlet, i.e. the steam outlet, is connected to the steam pipeline network; a conveying device for sending slag particles outside is arranged below the drum outlet; the conveying device is preferably a belt conveyor;

[0024] The second heat exchanger comprises a cylinder, two ends of which are respectively provided with a tail gas inlet and a tail gas outlet; the tail gas inlet is connected to the high-temperature dust-containing gas outlet at the top end of the overflow pipe through a pipeline; a heat exchange tube is arranged in the second heat exchanger, two ends of the heat exchange tube, i.e. 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 a user; preferably, the heat exchange tube adopts a serpentine structure;

[0025] The steam power generation device comprises a steam turbine and a power generation device; the inlet of the steam turbine is connected to the steam outlet of the first heat exchanger, the steam outlet of the second heat exchanger and the steam outlet of the steam drum through a pipeline; the power generation device is sent to a power user through a power transmission and distribution device.

[0026] Further, a desulfurization and dust removal device is further arranged, the desulfurization and dust removal device comprises a lye tank, a circulating pump, a nozzle, a washing tower, a liquid storage tank, a liquid removal tower, an induced draft fan and a chimney;

[0027] The liquid removal tower is provided with a liquid remover in the middle or upper part; the lower part of the liquid removal tower is provided with a liquid outlet and is connected to the inlet pipeline of the circulating pump; the top of the liquid removal tower is provided with a gas outlet and is connected to the chimney through a pipeline and an induced draft fan to be discharged to the atmosphere;

[0028] A washing tower, an inlet end of which is connected to a top end of the overflow pipe of the cyclone heat exchanger or an exhaust gas outlet of the second heat exchanger through a pipeline; a liquid storage tank is arranged at a lower part of the washing tower and is used for storing alkali liquor, and an outlet end of the liquid storage tank is connected to a liquid removal tower;

[0029] An alkali liquor tank, an outlet end of which is connected to a nozzle through a pipeline and a circulating pump, and the nozzle is arranged in a middle upper part of the washing tower.

[0030] Preferably, the power generation device is connected to a blast furnace, a steelmaking device, a steel rolling device and a green power user through a power transmission and distribution device.

[0031] Preferably, an air cushion and a water cushion are arranged in a feeding channel of the cyclone heat exchanger cylinder, and an inlet of the air cushion and the water cushion is connected to compressed air and water respectively; preferably, the air cushion and the water cushion are respectively arranged in a 1 / 4 circular arc along a circumferential tangential inlet in the cylinder, and the inlet of the air cushion and the water cushion is connected to compressed air and water respectively.

[0032] Preferably, a side wall of the cyclone heat exchanger cylinder is respectively provided with a heat insulation wear-resistant lining, a water-cooled wall and a steel plate from inside to outside; the heat insulation wear-resistant lining is preferably made of silicon carbide; preferably, the water-cooled wall is provided with a water-cooled wall cold water inlet connected to a deoxygenated water pipeline, and a water-cooled wall hot water outlet connected to an inlet end of the steam drum.

[0033] Preferably, an upper part of the cyclone heat exchanger cylinder is a cylindrical cylinder, and a lower part is a reverse conical cylinder; preferably, an included angle between a generatrix of the reverse conical cylinder and a horizontal plane is 20-80°, preferably 20-60°, or further preferably 20-40°.

[0034] Preferably, the overflow pipe is a constant-diameter circular pipe or an upper diameter expansion pipe with an upper diameter being 1-2 times of a lower diameter.

[0035] In the liquid blast furnace slag granulation and waste heat recovery system provided by the application:

[0036] The cyclone heat exchange device is used for heat recovery after heat exchange of the granulation gas and the high-temperature slag particles. The granulation device is used for conveying and granulating the molten slag. The waste heat recovery device is used for heat recovery of the slag particles and conveying of the low-temperature tail slag. The steam power generation device converts heat energy into electric energy to supply power to users. The desulfurization and dust removal device is used for purifying and discharging the exhaust gas.

[0037] The cyclone heat exchange device mainly comprises a cyclone heat exchanger, a spiral pipe 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 pipe bundle at the head and tail respectively; the spiral pipe bundle is arranged in the overflow pipe, and a pipe bundle water inlet is connected to the hot water pump, and a pipe bundle gas outlet is communicated with the steam drum. Steam is discharged from a steam outlet of the steam drum to a steam turbine after gas-liquid separation.

[0038] The cyclone heat exchanger is coaxially formed by an overflow pipe and a cylinder body, wherein the cylinder body comprises a column section and a cone section. The cylinder body of the cyclone heat exchanger is divided into three layers in the thickness direction, and the three layers from inside to outside are an adiabatic wear-resistant lining, a water-cooled wall and carbon steel or low alloy steel. The adiabatic wear-resistant lining can normally work at 1000-1500 ℃ and has high wear resistance and impact resistance, and is preferably made of silicon carbide or CoCrAlTaY material.

[0039] The water-cooled wall is used to improve the impact resistance and wear resistance of the lining, solve the problem of lining falling off, and recover the heat of high-temperature slag. The water-cooled wall is located on the outside of the cylinder body of the cyclone heat exchanger. Deaerated water enters the water-cooled wall through the cold water inlet of the water-cooled wall, and the hot water outlet of the water-cooled wall is connected with a steam drum. The deaerated water in the steam drum is connected with a hot water pump through a deaerated water outlet.

[0040] The air cushion and the water cushion are slots provided on the wall surface of the inlet pipe wall of the cyclone heat exchanger. The air cushion and the water cushion are respectively connected with compressed air and water, and are used to sweep and blow the blast furnace slag to prevent the un-solidified high-temperature slag particles from sticking to the wall.

[0041] In the cyclone heat exchanger, the blast furnace slag migrates to the side wall under the action of centrifugal force and gravity, and is collected and discharged through a discharge valve after moving to the slag discharge port along the gas. The high-temperature dust-containing gas is discharged from the overflow pipe at the top of the cyclone heat exchanger. The deaerated water enters the steam drum and is preheated, and then is evenly distributed into each spiral pipe of the spiral pipe bundle through the hot water pump connection pipe bundle water inlet. The high-temperature deaerated water flows downward along the spiral pipe bundle and is heated by the gas outside the pipe. In the spiral pipe bundle, the high-temperature water is first heated to saturation, and then the saturated water is continuously heated to occur nucleate boiling. Forced convection evaporation occurs until the water becomes saturated steam or superheated steam, which is discharged from the pipe bundle gas outlet to the steam drum for gas-liquid separation, and the steam is discharged from the steam outlet at the top of the steam drum to the steam turbine.

[0042] The spiral pipe bundle is spirally wound in several layers. In order to ensure compact structure and uniform heating of the heat exchange pipes and reduce the thermal deviation of each heat exchange pipe, the length of each heat exchange pipe is basically the same, the spiral rising angle is about 2-5°, and multi-start spiral pipes can be designed for each layer of spiral pipes to increase the heat exchange area.

[0043] The compressed air and water enter the inside of the injector to mix, under the action of the high pressure air, the water is atomized into liquid drops with a diameter of 50-500 um, and is sprayed out from the injector outlet along with the air, shearing the molten slag which freely falls in the flow guide cover after being discharged from the blast furnace, the slag flow is broken into slag drops under the shearing and impacting action of the high speed jet flow; heat exchange occurs between the slag drops and the air and water, so that the molten slag solidifies into solid particles with a particle size of 1-5 mm, and the water completely vaporizes into water vapor. The granulated and cooled blast furnace slag continues to fly forward in the flow guide cover along with the high temperature air and water vapor, and enters the cyclone heat exchange device.

[0044] The high temperature dust-containing gas after the cyclone heat exchange enters the second heat exchanger to further recover the heat of the gas, deoxygenated water is introduced into the heat exchange pipe, the deoxygenated water exchanges heat with the high temperature dust-containing gas outside the pipe to produce saturated or superheated steam which enters the steam turbine, and the dust-containing gas after heat exchange enters the desulfurization and dust removal device for purification treatment.

[0045] The waste heat recovery device comprises 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 is internally provided with a cylindrical heat exchange pipe bundle, deoxygenated water is introduced into the heat exchange pipe, steam is introduced into the steam pipe network from the outlet, and the low temperature slag falls onto the conveying device from the slag discharge port at the bottom of the drum of the first heat exchanger. The second heat exchanger is provided with a heat exchange pipe, deoxygenated water is introduced into the heat exchange pipe, steam is introduced into the steam grinding device from the outlet, and the tail gas after heat exchange enters the desulfurization and dust removal device for purification.

[0046] The motor drives the rotation shaft to rotate the drum, the high temperature slag enters the drum through the (star type) discharge valve, deoxygenated water enters the heat exchange pipe bundle to exchange heat with the high temperature slag outside the pipe, the liquid water completely vaporizes into saturated or superheated steam which is discharged from the steam outlet on the drum to the steam turbine. The cooled blast furnace slag is conveyed to the fertilizer and cement plant for further comprehensive utilization.

[0047] The steam power generation device comprises a steam turbine and a power generation device. The saturated or superheated water vapor produced by the cyclone heat exchange device and the waste heat recovery device is combined and then enters the steam turbine to convert the heat energy of the gas into electric energy, which provides electric energy for users such as blast furnace ironmaking and oxygen top blown converter steelmaking, and at the same time, the green power device is used as a supplementary power source for the blast furnace and the converter to ensure the normal operation of the blast furnace and the converter.

[0048] The desulfurization and dust removal device comprises a lye tank, a circulating pump, a washing tower, a liquid storage tank, a liquid removal tower, a nozzle, an induced draft fan and a chimney. The lye tank is connected with the circulating pump, the circulating pump is connected with the nozzle, the nozzle is located on the washing tower, the liquid storage tank is located directly below the washing tower and is connected with the washing tower and the liquid removal tower respectively, the induced draft fan is connected with the gas outlet pipe at the top of the liquid removal tower and discharges the gas into the chimney.

[0049] In the desulfurization and dust removal device, the air and water vapor after waste heat recovery entrain some small-particle-size blast furnace slag particles and SO2 gas generated in the granulation stage, and enter the tower from the gas inlet at the top of the washing tower for purification treatment. An alkaline solution (such as NaOH solution) is used as the absorbent, stored in the lye tank, and used to absorb SO2 in the flue gas. The lye is delivered to the nozzle on the washing tower by the circulating pump, and the lye is sprayed from the nozzle into the gas flow from bottom to top, causing the gas-liquid two-phase high-speed counterattack. When the momentum of the gas-liquid two-phase reaches balance, a highly turbulent foam zone is formed, and the gas-liquid two-phase is in high-speed turbulent contact in the foam zone. The contact surface area is large, and these contact surfaces are constantly and rapidly renewed, achieving high-efficiency washing and purification effect. The mixed gas after washing is subjected to gas-liquid separation, and the liquid enters the liquid storage tank at the lower part of the washing tower, and is delivered to the circulating pump through the liquid outlet. The purified gas enters the liquid removal tower through the connecting port at the upper end of the liquid storage tank, and the entrained liquid is removed by the liquid removal device. The tail gas meeting the emission standard is sent to the chimney by the induced draft fan and discharged into the atmosphere.

[0050] In the method using the liquid blast furnace slag granulation and waste heat recovery system, compressed air and water are mixed in the ejector cavity of the granulator ejector through the gas and water interfaces on the ejector, form a high-speed jet into the flow guide cover, shear the molten blast furnace slag falling freely into the flow guide cover 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 jet. The granulated blast furnace slag enters the cyclone heat exchanger of the cyclone heat exchange device along with the high-temperature air and water vapor, and is rapidly separated in the cyclone heat exchanger due to the large difference in density between the gas and the solid phase. The deoxygenated water is pressurized by the hot water pump and delivered to the spiral pipe bundle, exchanges heat with the high-temperature gas outside the pipe to obtain saturated or superheated steam, and is delivered to the second heat exchanger of the waste heat recovery device. The high-temperature blast furnace slag separated from the gas enters the first heat exchanger of the waste heat recovery device through the discharge valve, and the heat exchange pipe bundle in the first heat exchanger drum is connected to the cooling water. The liquid water rapidly absorbs the heat of the high-temperature blast furnace slag in the drum to become water vapor, and the temperature of the high-temperature blast furnace 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 back for recycling by the conveying device. The saturated or superheated steam generated by the steam turbine, the first heat exchanger and the second heat exchanger of the cyclone heat exchange device enters the steam turbine, and the heat energy is converted into kinetic energy to drive the power generation device. After the heat energy is converted into electrical energy, the power distribution device supplies power to the steelmaking equipment, rolling equipment or green electricity users.

[0051] Further, the heat-exchanged gas enters the desulfurization and dust removal device, the lye in the lye tank is sprayed from the nozzle into the gas flow by the circulating pump from bottom to top, and high-efficiency washing and purification effect is achieved. The mixed gas after washing is subjected to gas-liquid separation, the liquid reenters the liquid storage tank and is recycled, and the purified gas is discharged after the entrained liquid is removed by the mist eliminator.

[0052] In the method described in the present application:

[0053] The granulating device adopts an injector, compressed air and water enter the injector cavity respectively, mix to form a high-speed jet, and then enter the guide cover. The molten blast furnace slag falling freely into the guide cover is sheared. Under the shearing action of the high-speed jet, the molten blast furnace slag is broken into particles. After the molten slag particles contact and exchange heat with air and water, solidification occurs on the surface. The inside of the particles is still molten. Water vaporizes into water vapor, and air absorbs heat and increases in temperature. The molten slag particles enter the cyclone heat exchanger with the mixed gas of high-temperature air and water vapor. In the cyclone heat exchanger, the mixed gas and the molten slag particles further contact and exchange heat. The mixed gas absorbs heat and increases in temperature to 500 DEG C. The molten slag particles completely solidify and decrease in temperature to 700 DEG C. The activity of the granulated blast furnace slag mainly depends on the content of its glass body. Only when the cooling rate is greater than the critical cooling rate, can a high content of glass state be obtained.

[0054] In the present application, the molten slag can be rapidly quenched, and the cooling rate is about 200 DEG C / s, which is much greater than the critical cooling rate of 10 DEG C / s. The particle size of the granulated slag is basically distributed in 1-5 mm, the size is uniform, and the glass content is as high as 100%.

[0055] The glass content of the granulated slag obtained by water quenching method is 95% (Ren Yubin. Design of water flushing slag system of Shougang Changgang 9# blast furnace [J]. Jiangxi Building Materials, 2021, 04: 238-24).

[0056] The glass content of the granulated slag obtained by air quenching method is 95% (Zou Youwu. Japanese development of blast furnace slag sensible heat comprehensive recovery technology [J]. Anshan Technology, 1990, 10: 3-14).

[0057] In the cyclone field, the centrifugal force received by the dispersed phase is much greater than the gravity received by the dispersed phase; at the same time, the dispersed phase only needs to migrate to the edge wall in the cyclone heat exchanger, so the separation speed, separation precision and separation efficiency of the cyclone heat exchanger are much higher than those of the gravity sedimentation means, and the volume of the equipment is much smaller than that of the gravity sedimentation equipment. The density difference between the gas and the solid phase is large, and rapid separation is realized in the cyclone heat exchanger.

[0058] In addition, the spiral heat exchange pipe is arranged in the overflow pipe of the cyclone heat exchanger to realize efficient recycling of heat. Compared with the straight pipe type, firstly, in terms of heat exchange, the structure of the spiral pipe can substantially improve the heat transfer efficiency, especially for boiling and evaporation, the critical heat flux is obviously increased, and the local cross flow along the pipe (i.e. secondary circulation) and counter-flow heat exchange inside and outside the pipe can also improve the heat exchange capacity; secondly, the structure of the spiral pipe can be relatively free expansion, so that excessive thermal stress is not generated; finally, the arrangement of the spiral pipe can ensure compact design, thereby reducing the occupied space. Therefore, based on comprehensive consideration of total cost, design and manufacturing experience, thermal performance and operating characteristics, the spiral heat exchange pipe is preferably used for heat exchange.

[0059] The deoxygenated water is delivered to the spiral pipe after being pressurized by the hot water pump, and heat exchanged with the high-temperature gas outside the pipe to obtain saturated or superheated steam. Taking the water consumption of 1 ton of slag in the present application as 0.13t and the water pump power as about 0.03kW·h as an example, compared with the traditional water slagging process, the water consumption is only 4.3% of the water slagging process, which is beneficial to energy saving and emission reduction of the steel enterprise; at the same time, due to the substantial reduction of water consumption, the production of acid gas is reduced, thereby reducing the pollution to the environment. If the outlet air pressure of the compressor is calculated as 0.4MPa, the power of the compressor is about 3kW·h / ton of slag (SINOPEC Shanghai Engineering Co., Ltd. Chemical Process Design Manual [M]. Beijing: Chemical Industry Press, 2018: 1275-1276). The total energy consumption in the slag granulation process is similar to that of the water slagging method, which is 8% of the air quenching method and 17% of the centrifugal granulation method.

[0060] The gas after cyclone heat exchange enters the second heat exchanger for further heat recovery. The deoxygenated water is introduced into the heat exchange pipe of the second heat exchanger, and is vaporized into saturated or superheated steam after heat exchange with the high-temperature gas outside the pipe. The tail gas after heat exchange enters the desulfurization and dust removal device for purification. The lye in the lye tank is sprayed into the gas flow from bottom to top by the nozzle through the circulating pump, achieving high-efficiency washing and purification effect. The mixed gas after washing is separated into liquid and gas, the liquid is recycled into the liquid storage tank, and the purified gas is discharged after removing the entrained liquid by the demister.

[0061] The high-temperature slag separated from the gas enters the first heat exchanger through the star-shaped discharge valve to continue recycling the heat of the slag. The first heat exchanger is provided with a heat exchange pipe, and cold water is introduced into the pipe. The liquid water is rapidly converted into water vapor in the first heat exchanger, and the temperature of the blast furnace slag is further reduced to below 100℃. The low-temperature slag particles flow out of the bottom of the first heat exchanger and are transported to a fertilizer plant or a cement plant by a conveying device for further recycling.

[0062] The saturated or superheated steam obtained by the cyclone heat exchanger, the first heat exchanger and the second heat exchanger is gathered and enters the steam turbine to convert the heat energy of the steam into electric energy, which provides power for the blast furnace and the oxygen top-blown converter of the user.

[0063] The device of the application has compact structure and small floor area, and can realize effective separation of gas and solid and produce high-grade steam. When the diameter of the cyclone heat exchange device is designed as Φ5500mm and the slag treatment capacity is 2400t / d (generally, the blast furnace is intermittent slagging, and the cycle is 3h, of which the slagging time is 1h), the recovered heat can produce saturated or superheated steam, and the separation of high-temperature gas and slag can be realized at the same time.

[0064] When the slag treatment capacity in the water granulation 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 the heat cannot be recovered in the granulation tower.

[0065] When the slag treatment capacity in the air granulation process is 800t / d (generally, the blast furnace is intermittent slagging, and the cycle is 3h, of which the slagging time is 1h), the main size of the air tunnel for granulation and heat exchange is: length 25m, width 7m, height 13m. The cyclone dust collector cylinder diameter for realizing gas-solid separation is Φ5200mm. Steam cannot be directly produced in the air tunnel, and an additional boiler device is needed to produce steam, and the overall equipment floor area is much larger than that of the cyclone heat exchange device in the application.

[0066] When the slag treatment capacity in the centrifugal process is 320t / d, if the molten slag with a mass flow rate of 2400t / d is treated, 8 centrifugal rapid cooling granulation devices with a diameter of Φ4200mm are needed in parallel. In the centrifugal rapid cooling granulation device, steam cannot be directly produced, and an additional waste heat boiler device is needed to produce steam, and the overall equipment floor area is much larger than that of the cyclone heat exchange device in the application. In addition, in the centrifugal rapid cooling granulation device, effective separation of gas and solid cannot be realized, and a part of solid particles will enter the waste heat boiler with high-temperature gas, which reduces the heat exchange effect and service life of the waste heat boiler.

[0067] The application has the following advantages:

[0068] The application is based on the micro-interface oscillation rapid cooling mechanism in the cyclone field, and the structure of the cyclone heat exchanger is optimized to increase the amplitude and frequency of the micro-interface oscillation, so that the rapid cooling rate of the blast furnace slag is ≥200℃ / s, the glass content of the blast furnace slag after granulation and cooling is 100%, and the heat exchange and separation effect of the cyclone heat exchanger is strengthened. After the high-temperature slag particles enter the cyclone heat exchanger, the rapid oscillation is generated by the pulsating rotation, the interface oscillation is beneficial to thinning the thickness of the boundary layer, increasing the heat transfer coefficient and thus strengthening the heat exchange; at the same time, the interface oscillation makes the local flow field around the slag particles change constantly, so that more cold air can contact the particle surface, increase the heat exchange area, and be beneficial to strengthening the heat exchange; in addition, the interface oscillation is beneficial to the internal movement of the molten state molecules of the slag particles, strengthens the relative flow in the slag particles, realizes the convective heat transfer in the slag particles, increases the heat transfer coefficient and thus strengthens the heat exchange process.

[0069] 2) The cyclone heat exchanger of the present application is based on the coupling design of cyclone desolidification and waste heat recovery, fully utilizes the advantage of fast cyclone separation speed, greatly shortens the separation time of gas-solid two-phase mixture, and compared with the conventional system of first granulation, then dust removal and finally waste heat recovery through waste heat boiler, the subsequent separation and heat exchange process is greatly shortened, the number of devices required by the system is significantly reduced, so that the cyclone heat exchanger has the advantages of large operation flexibility, high separation efficiency and precision, high waste heat recovery efficiency, high space utilization, compact structure, small land occupation, high economic benefit, convenient maintenance and the like.

[0070] The system described in the present application is used for granulation and heat recovery of high-temperature liquid slag. The slag temperature is 1400-1600℃, the rated mass flow rate is 300t / h, and the system operating pressure is-7kPa. BRIEF DESCRIPTION OF DRAWINGS

[0071] Figure 1 The process flow diagram of the embodiment of the liquid blast furnace slag granulation and waste heat recovery system described in the present application is shown in the figure.

[0072] Figure 2 The structure diagram of the cyclone heat exchange device and the granulation device in the embodiment of the liquid blast furnace slag granulation and waste heat recovery system described in the present application is shown in the figure.

[0073] Figure 3 The structure diagram of the waste heat recovery device and the steam power generation device in the embodiment of the liquid blast furnace slag granulation and waste heat recovery system described in the present application is shown in the figure.

[0074] Figure 4 The structure diagram of the desulfurization and dust removal device in the embodiment of the liquid blast furnace slag granulation and waste heat recovery system described in the present application is shown in the figure. DETAILED DESCRIPTION

[0075] Referring to Figures 1 to 4 The liquid blast furnace slag granulation and waste heat recovery system described in the present application comprises a cyclone heat exchange device 100, a granulation device 200, a waste heat recovery device 300 and a steam power generation device 400; wherein,

[0076] The cyclone heat exchange device 100 comprises:

[0077] The cyclone heat exchanger 1 comprises:

[0078] The barrel 11 is provided with a feed inlet and a feed channel 111 on one side of the upper part, the lower part of the barrel 11 is conical, and the bottom is provided with a slag discharge port 112 and a discharge valve 113; preferably, the discharge valve 113 is a star-shaped discharge valve;

[0079] The overflow pipe 12 is vertically inserted into the upper part of the barrel 11 at the lower part; the top end of the overflow pipe 12 is provided with a high-temperature dust-containing gas outlet 121;

[0080] A spiral tube bundle 13 is arranged in the overflow pipe 12, and two ends of the spiral tube bundle 13, i.e. a tube bundle water inlet 131 and a tube bundle gas outlet 132, are located outside the overflow pipe 12;

[0081] A steam drum 2 is connected to a deoxygenated water pipeline at an inlet end, and is provided with a deoxygenated water outlet 201 and 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. A steam outlet 202 on the steam drum 2 is connected to a steam pipeline network.

[0082] The granulation device 200 comprises an injector 4 and a flow guide cover 5. The injector 4 outlet corresponds to the flow guide cover 5 inlet, and the flow guide cover 5 outlet is connected to the cyclone heat exchanger 1 feed channel 111 of the cyclone heat exchange device 100. The flow guide cover 5 top surface is provided with a molten slag inlet 51.

[0083] The injector 4 comprises an injector provided with a compressed air interface 401 and a water interface 402. The compressed air interface and the water interface are respectively connected to a compressed air pipe and a water pipe. The injector 4 outlet is connected to the flow guide cover 5 inlet. Preferably, the injector 4 is a Venturi injector.

[0084] The waste heat recovery device 300 is arranged below the cyclone heat exchange device 100, and comprises:

[0085] The first heat exchanger 6 is a drum-type heat exchanger, comprising a drum 61 and a driving motor 62. The drum 61 is provided with a feed inlet 611 and a discharge outlet 612 at two ends, respectively. The feed inlet 611 is connected to the slag discharge port 112 of the cyclone heat exchanger 1 cylinder 11. The drum 61 end provided with the feed inlet 611 is further provided with a water inlet 613 connected to a deoxygenated water pipeline, and the opposite end is provided with a steam outlet 614. The drum 61 is provided with a heat exchange tube bundle 63 inside. The heat exchange tube bundle 63 inlet is connected to a deoxygenated water pipeline, and the heat exchange tube bundle 63 outlet, i.e. the steam outlet, is connected to a steam pipeline network. A conveying device 7 for sending slag particles outside is arranged below the drum 61 discharge outlet 612. The conveying device 7 is preferably a belt conveyor.

[0086] The second heat exchanger 8 comprises a cylinder 81 provided with a tail gas inlet 811 and a tail gas outlet 812 at two ends, respectively. The tail gas inlet 812 is connected to the high-temperature dust-containing gas outlet 121 at the top end of the overflow pipe 12 through a pipeline. The second heat exchanger 8 is provided with a (serpentine) heat exchange tube 82 inside. The heat exchange tube 82 is provided with a water inlet 821 and a steam outlet 822 at two ends. The water inlet 821 is connected to a deoxygenated water pipeline, and the steam outlet 822 is connected to a steam pipeline network or a user.

[0087] The steam power generation device 400 comprises a steam turbine 22 and a power generation device 23; the inlet of the steam turbine 22 is connected to the steam outlet 614 of the first heat exchanger 6, the steam outlet 822 of the second heat exchanger 8 and the steam outlet 202 of the steam drum 2 through pipes; the power generation device 23 is connected to the power distribution device 24 to send power to the electric users, including the blast furnace 600, the steelmaking equipment 700, the rolling equipment 800 and the green electric users 900.

[0088] Referring to Figure 1 , Figure 4 , the desulfurization and dust removal device 500 is further provided, which comprises a lye tank 9, a circulating 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 liquid removal tower 19 is provided with a liquid remover 191 in the middle or upper part; the lower part of the liquid removal tower 19 is provided with a liquid outlet 192 connected to the inlet pipe of the circulating pump 10; the top of the liquid removal tower 19 is provided with a gas outlet 193 connected to the chimney 21 through pipes and the induced draft fan 20 to discharge to the atmosphere.

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

[0091] The lye tank 8 is connected to the nozzle 16 through pipes and the circulating pump 9, and the nozzle 16 is arranged in the middle or upper part of the washing tower 17.

[0092] Preferably, the gas cushion 114 and the water cushion 115 are arranged in the feed passage 111 of the barrel 11 of the cyclone heat exchanger 1, and the inlets of the gas cushion and the water cushion are respectively connected to compressed air and water; preferably, the inlets of the gas cushion and the water cushion are respectively arranged in the 1 / 4 circular arc of the circumferential tangential inlet of the barrel 11 of the cyclone heat exchanger 1, and the inlets of the gas cushion and the water cushion are respectively connected to compressed air and water.

[0093] Preferably, the side wall of the barrel 11 of the cyclone heat exchanger 1 is respectively provided with a heat-insulating wear-resistant lining, a water-cooled wall and a steel plate from the inside to the outside; the heat-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 a deoxidized water pipeline, and a water-cooled wall hot water outlet 117 connected to the inlet end of the steam drum 2.

[0094] Preferably, the upper part of the barrel 11 of the cyclone heat exchanger 1 is a cylindrical barrel, and the lower part is a reverse conical barrel; preferably, the included angle between the generatrix of the reverse conical barrel and the horizontal plane is 20-80°, preferably 20-60°, or further preferably 20-40°.

[0095] Preferably, the overflow pipe 12 is a constant diameter pipe or an upper diameter expansion pipe with the upper diameter being 1-2 times the lower diameter.

[0096] Embodiment

[0097] The molten slag from the blast furnace falls freely into the top of the flow guide cover with a slag inlet having an area of 600mm x 600mm. The flow of the molten slag is relatively stable, with a rated mass flow rate of 5 tons per minute. Compressed air is mixed with water in the injector and is sprayed out as a high pressure jet, with the water being atomized into droplets having a particle size of 50-500um by the air; the molten slag stream is cut into slag droplets having a particle size of 1-5mm by the high pressure jet sprayed out by the injector, and exchanges heat with the air and the droplets at the same time. The droplets are completely vaporized into water vapor, and the air absorbs heat to become high temperature gas. The slag droplets are cooled and solidified into solid slag particles, and fly forward in the flow guide cover into the cyclone heat exchanger along with the gas. A water cushion and an air cushion having a width of 10mm and a length of 1000mm are provided on the wall surface of the inlet pipe of the cyclone heat exchanger, and are connected to compressed air and fresh water respectively, for sweeping and blowing the slag particles to prevent the high temperature slag particles from sticking to the wall and affecting the normal operation of the cyclone heat exchanger. The high temperature slag particles and the high temperature gas are rapidly 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.

[0098] The high temperature dust-containing gas is discharged from the overflow pipe at the top of the cyclone heat exchanger, and exchanges heat with the cooling medium in the spiral pipe bundle during the flow process to recover the heat of the high temperature gas. The cooling medium in the spiral pipe bundle is deoxygenated water, which is first delivered to the steam drum for preheating, and then delivered to the spiral pipe bundle by a hot water pump. The deoxygenated water is evenly distributed to each spiral pipe through the pipe bundle water inlet on the spiral pipe bundle, and is vaporized into superheated steam of 250℃-1.6MPA-9t / h after exchanging heat with the high temperature gas, and is collected at the pipe bundle gas outlet at the end of the spiral pipe bundle and then enters the steam drum for gas-liquid separation, and the separated steam is delivered to the steam turbine.

[0099] A silicon carbide (or CoCrAlTaY) lining is laid on the inner wall of the cylinder of the cyclone heat exchanger, and a water-cooled wall is provided on the outside. The deoxygenated water enters through the cold water inlet of the water-cooled wall, exchanges heat with the high temperature substances in the cyclone heat exchanger, and then is delivered to the steam drum through the hot water outlet of the water-cooled wall for further heat exchange.

[0100] The high-temperature dust-containing gas discharged from the overflow pipe goes to a second heat exchanger, which has heat exchange tubes built therein. Deaerated water is introduced into the tubes, and the deaerated water exchanges heat with the high-temperature dust-containing gas outside the tubes to vaporize into superheated steam of 250℃-1.6MPA-9t / h. The generated steam goes to a steam turbine. The heat-exchanged dust-containing gas goes to a desulfurization and dust removal device for purification and then is discharged. The heat-exchanged slag particles are discharged from a (star-shaped) discharge valve at the bottom of the cyclone heat exchanger into a roller of the first heat exchanger for further heat exchange. The heat exchange tube bundle is built in the roller, and deaerated water is introduced into the tube bundle. A motor drives a rotating shaft to keep the roller rotating at a uniform speed. The deaerated water in the heat exchange tube bundle exchanges heat with the high-temperature slag particles outside the tube bundle, and after absorbing heat, the deaerated water rapidly vaporizes into superheated steam of 250℃-1.6MPA-9t / h. The generated superheated steam is transported to the steam turbine 31. The cooled slag particles fall into a conveying device from a slag discharge port at the bottom of the roller and are transported to a fertilizer and cement plant for further comprehensive utilization.

[0101] Since SO2 acidic gas is easily generated in the granulation process, the dust-containing gas discharged from the heat exchanger I enters a scrubbing tower for desulfurization and dust removal. NaOH solution is used as the absorbent and is stored in a lye tank. The lye is transported to a nozzle by a circulating pump, and after being sprayed out of the nozzle, the lye reacts with SO2 in the gas to generate Na2SO3. The purified gas and the excess lye flow into a lye storage tank at the lower part of the scrubbing tower. The gas enters a liquid removal tower from an interface at the upper part of the lye storage tank, and under the action of the liquid remover, the liquid foam mixed in the gas is removed. The excess lye enters the liquid removal tower from an interface at the lower part of the lye storage tank and is discharged from a liquid outlet to enter the circulating pump again. After desulfurization and dust removal, the gas temperature is ≤80℃, the SO2 concentration is ≤50mg / m 3 , and the particulate matter concentration is ≤10mg / m 3 . The gas is extracted by an induced draft fan and is discharged through a chimney to meet the standard.

[0102] The superheated steam generated by the cyclone heat exchange device and the waste heat recovery device converges and then enters a steam turbine to do work, converting the heat energy of the steam into electric energy. The electric energy provides a certain amount of power for the blast furnace ironmaking and the oxygen top-blown converter steelmaking, and at the same time, a green power device is used as a supplemental power source to ensure the normal operation of the blast furnace and the converter.

[0103] The above merely describes preferred embodiments of the present application and is not intended to limit the protection scope of the present application. Therefore, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

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, a waste heat recovery device and a steam power generation 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 comprises a cylindrical body, with an exhaust gas inlet and an exhaust gas outlet at each end thereof; the exhaust gas inlet is connected to the high-temperature dust-laden gas outlet at the top of the overflow pipe through a pipeline; a heat exchange tube is arranged in the second heat exchanger, with a water inlet and a steam outlet at each end of the heat exchange tube; the water inlet is connected to the deoxygenated water pipeline, and the steam outlet is connected to the steam network or the user; the heat exchange tube adopts a serpentine structure; The steam power generation device includes a steam turbine and a power generation device; the inlet of the steam turbine is connected to the steam outlet of the first heat exchanger, the steam outlet of the second heat exchanger and the steam outlet of the steam drum through a pipeline; the power generation device transmits electricity to the electricity user through the power transmission and distribution device.

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: The power generation device transmits electricity to blast furnaces, steelmaking equipment, rolling equipment and green electricity users through power transmission and distribution equipment.

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 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.

6. 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.

7. 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.

8. 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.

9. 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.

10. 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.

11. The liquid blast furnace slag granulation and waste heat recovery system according to claim 7, characterized in that: The included angle between the generatrix of the inverted conical cylinder and the horizontal plane is 20-60°.

12. The liquid blast furnace slag granulation and waste heat recovery system according to claim 8, characterized in that: The included angle between the generatrix of the inverted conical cylinder and the horizontal plane is 20-60°.

13. The liquid blast furnace slag granulation and waste heat recovery system according to claim 9, characterized in that: The included angle between the generatrix of the inverted conical cylinder and the horizontal plane is 20-60°.

14. 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 conical cylinder and the horizontal plane is 20-60°.

15. 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.

16. 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. Under the shear and impact of the high-speed jet, the molten blast furnace slag is broken and solidified into solid particles; the granulated blast furnace slag enters the cyclone heat exchanger of the cyclone heat exchange device 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 bundle, 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 being separated 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 turns 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 out by the conveying device for recycling. The saturated or superheated water vapor generated by the steam drum of the cyclone heat exchange device, the first heat exchanger and the second heat exchanger enters the steam turbine, and the thermal energy is converted into kinetic energy to drive the power generation device. After the thermal energy is converted into electrical energy, it is supplied to the steelmaking equipment, rolling equipment or green electricity users through the power transmission and distribution device.

17. The method of liquid blast furnace slag granulation and waste heat recovery system according to claim 16, 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.

18. The method of 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.

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