Liquid slag recovery and storage system based on fused salt energy storage

Abstract

The utility model discloses a liquid slag recovery and storage system based on fused salt energy storage, which relates to the field of waste heat utilization and comprises a high-temperature fused salt tank and a low-temperature fused salt tank, an outlet of the low-temperature fused salt tank is connected into an inlet of the high-temperature fused salt tank through a heat extraction pipeline, and an oil-salt heat exchanger is arranged on the heat extraction pipeline to form heat exchange. An oil-salt heat exchange pipe of the oil-salt heat exchanger extends to the moving fluidized bed, the moving fluidized bed bears slag particles obtained after liquid slag is crushed and granulated, and the oil-salt heat exchange pipe exchanges heat with the slag particles; an outlet of the high-temperature molten salt tank is connected into an inlet of the low-temperature molten salt tank through a heat release pipeline, a superheater, an evaporator and a preheater are sequentially arranged on the heat release pipeline and form heat exchange with the heat release pipeline, and an electric heating device is installed on the high-temperature molten salt tank. Intermittent high-temperature sensible heat resources are converted into continuously adjustable and controllable high-temperature, high-pressure and high-quality steam which is stably utilized, valley cutting and peak filling are achieved, the heat energy utilization rate is increased, and the production cost is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of waste heat utilization, especially relates to a liquid molten slag recovery and storage system based on molten salt energy storage. BACKGROUND

[0002] The furnace slag has a large stock and high temperature, and contains rich waste heat and energy resources, and the sensible heat of the high-temperature molten slag has not been effectively utilized. The high-temperature molten slag is generally quenched by water, and the waste heat utilization rate is low. At present, the waste heat is recovered by granulating the molten slag and using a moving bed heat transfer mode, but this technology has the risk of serious wear of the pressure pipeline and pipe explosion, and because the molten slag is discharged intermittently and the amount of molten slag changes instantaneously, the fluctuation is large.

[0003] A liquid molten slag sensible heat recovery and storage system based on molten salt energy storage is disclosed in Chinese patent (publication number CN 118621070 A), which granulates the high-temperature molten slag generated by a blast furnace by using a dry method, converts most of the sensible heat of the molten slag into high-temperature flue gas, heats the low-temperature molten salt into high-temperature molten salt, and stores the high-temperature molten salt in a high-temperature molten salt tank. The high-temperature molten salt is introduced into a molten salt steam superheater to heat the saturated steam, generating superheated steam and solving the problem of intermittent gas fluctuation. When the flue gas and the high-temperature molten slag are heat exchanged, high-pressure gas needs to be introduced to meet the air volume requirement for cooling the molten slag, which also makes the gas flowing through the high-temperature molten slag have strong fluidity, the movement of solid particles in the gas flow is relatively complex, and the particles are easy to escape, so the recovery efficiency is relatively low, and dust removal and purification equipment needs to be added. The filter bag and electrode components used need to be replaced regularly, which not only increases energy consumption but also has the risk of air pollution. UTILITY MODEL CONTENTS

[0004] The utility model aims at the defects of the prior art, and provides a liquid molten slag recovery and storage system based on molten salt energy storage, which heats the slag particles in an oil salt heat exchanger, then heats the low-temperature molten salt in a heat extraction pipeline into high-temperature molten salt and stores the high-temperature molten salt in a high-temperature molten salt tank, then exchanges heat between the high-temperature molten salt and a superheater to heat the saturated steam into superheated steam to meet the demand of a steam turbine, converts the intermittent high-temperature sensible heat resources into continuous adjustable and controllable high-temperature, high-pressure, and high-quality steam and stably utilizes the steam, fills the valley and peaks, greatly improves the thermal energy utilization rate, and reduces the production cost.

[0005] In order to achieve the above-mentioned purpose, the following technical scheme is adopted:

[0006] The utility model provides a kind of liquid slag recovery storage system based on molten salt energy storage, including high-temperature molten salt tank and low-temperature molten salt tank, the outlet of low-temperature molten salt tank is connected to the inlet of high-temperature molten salt tank by heat extraction pipeline, oil salt heat exchanger is equipped on heat extraction pipeline and forms heat exchange, and oil salt heat exchange tube of oil salt heat exchanger extends to mobile fluidized bed, mobile fluidized bed carries slag particle after liquid slag crushing granulation, and oil salt heat exchange tube exchanges heat with slag particle;The outlet of high-temperature molten salt tank is connected to the inlet of low-temperature molten salt tank by heat release pipeline, superheater, evaporator and preheater are sequentially arranged on heat release pipeline, and heat exchange is formed with heat release pipeline respectively, and electric heating device is installed on high-temperature molten salt tank.

[0007] Further, the segment of the oil salt heat exchange tube located in the mobile fluidized bed is continuously curved and in a serpentine shape, and the segment located outside the mobile fluidized bed is coiled on the heat extraction pipeline, and the oil salt heat exchange tube is filled with heat conducting oil.

[0008] Further, the mobile fluidized bed is connected to a centrifugal granulator upstream, the inlet end of the centrifugal granulator receives liquid slag, the outlet of the centrifugal granulator faces the mobile fluidized bed, and the mobile fluidized bed is connected to a slag bin downstream.

[0009] Further, the superheater, the evaporator and the preheater are connected to a steam pipeline of a steam turbine, and a condenser is further arranged on the steam pipeline.

[0010] Further, the steam turbine is further connected to a reheater, the heat release pipeline is connected to a heat release branch pipeline parallel to the superheater, and the reheater exchanges heat with the heat release branch pipeline.

[0011] Further, one end of the heat release branch pipeline is connected to the heat release pipeline between the superheater and the outlet of the high-temperature molten salt tank, and the other end of the heat release branch pipeline is connected to the heat release pipeline between the superheater and the evaporator.

[0012] Further, the output end of the steam turbine is connected to a generator, and the generator is connected to the electric heating device.

[0013] Compared with the prior art, the utility model has the following beneficial effects:

[0014] The utility model aims at the problem that the recovery efficiency of waste heat utilization is relatively low after high-temperature molten slag exchanges heat with gas, heats oil salt heat exchanger by slag particle, heats low-temperature molten salt in heat extraction pipeline to high-temperature molten salt, stores high-temperature molten salt in high-temperature molten salt tank, exchanges heat between high-temperature molten salt and superheater, heats saturated steam to superheated steam to meet the demand of steam turbine, converts intermittent high-temperature sensible heat resource into continuous adjustable controllable high-temperature, high-pressure, high-quality steam and stably utilizes, fills peak in valley, greatly improves heat energy utilization rate, and reduces production cost. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1It is a schematic view of the liquid molten slag recovery and storage system based on molten salt energy storage in the embodiments of the present application.

[0016] Label explanation (in the order of first appearance): 1, centrifugal granulator; 2, moving fluidized bed; 3, slag bin; 4, oil-salt heat exchanger; 5, high-temperature molten salt tank; 6, low-temperature molten salt tank; 7, electric heating device; 8, superheater; 9, evaporator; 10, preheater; 11, reheater; 12, condenser; 13, generator; 14, steam turbine. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.

[0018] When the flue gas and the high-temperature molten slag are exchanged, high-pressure gas needs to be introduced to meet the air volume demand for cooling the molten slag, which also makes the gas flowing through the high-temperature molten slag strong in fluidity, and the movement of solid particles in the gas flow is relatively complex, which is easy to escape, so the recovery efficiency is relatively low; based on this, the present embodiment provides a liquid molten slag recovery and storage system based on molten salt energy storage, which converts the sensible heat of the intermittently generated high-temperature molten slag into continuous adjustable controllable high-temperature, high-pressure and high-quality steam through molten salt energy storage technology, solving the problem of unstable steam generation in the traditional method. The moving fluidized bed 2 and the oil-salt heat exchanger 4 are adopted to improve the recovery efficiency of the sensible heat of the molten slag, reduce the escape of solid particles, and reduce the burden of dust removal and purification equipment. By optimizing the heat exchange process, the replacement frequency of filter bags, electrodes and other components is reduced, and the energy consumption and air pollution hazards are reduced.

[0019] As shown in Figure 1 The liquid molten slag recovery and storage system based on molten salt energy storage mainly includes a high-temperature molten salt tank 5, a low-temperature molten salt tank 6, an oil-salt heat exchanger 4, a superheater 8, an evaporator 9 and a preheater 10. The high-temperature molten salt tank 5 is used to store high-temperature molten salt after heating. The low-temperature molten salt tank 6 stores initial low-temperature molten salt as the starting point of heat exchange. The heat extraction pipeline connects the low-temperature molten salt tank 6 and the high-temperature molten salt tank 5, which is the main channel for heating the molten salt. The oil-salt heat exchanger 4 is located on the heat extraction pipeline and heats the low-temperature molten salt through heat exchange. The moving fluidized bed 2 carries the slag particles after the liquid molten slag is broken and granulated, and exchanges heat with the oil-salt heat exchange pipe. The heat release pipeline leads the high-temperature molten salt from the high-temperature molten salt tank 5, which is used to transfer the heat energy of the high-temperature molten salt to other equipment. The superheater 8, the evaporator 9 and the preheater 10 are sequentially arranged on the heat release pipeline for heat exchange at different stages. The electric heating device 7 is installed on the high-temperature molten salt tank 5 and is used for auxiliary heating or maintaining the temperature of the molten salt.

[0020] The oil-salt heat exchanger 4 includes oil-salt heat exchange tubes that extend into the moving fluidized bed 2 and directly contact the slag particles to efficiently absorb the sensible heat of the molten slag. The moving fluidized bed 2 carries and breaks down the high-temperature molten slag produced by the blast furnace, allowing the slag particles to fully contact the oil-salt heat exchange tubes in a fluidized state, thereby improving the heat exchange efficiency.

[0021] Through the heat-removing pipeline and the heat-releasing pipeline, the low-temperature molten salt is heated into high-temperature molten salt, and then the heat energy is transferred to the superheater 8, the evaporator 9, and the preheater 10, finally producing superheated steam. The electric heating device 7 serves as an auxiliary heat source to ensure the stability of the molten salt temperature in the high-temperature molten salt tank 5, meeting the needs of subsequent heat exchange.

[0022] The system greatly improves the heat energy utilization rate through efficient heat exchange and energy storage technology, allowing intermittent high-temperature sensible heat resources to be stably utilized. Due to the improvement of heat energy utilization rate and the reduction of energy consumption, the overall production cost is effectively controlled. The burden on dust removal and purification equipment and the frequency of component replacement are reduced, air pollution risks are reduced, and the development concept of green and low carbon is met.

[0023] It can be understood that the high-temperature molten salt tank 5 and the low-temperature molten salt tank 6 in the embodiment are relative temperatures, that is, the temperature of the molten salt in the high-temperature molten salt tank 5 is higher than that in the low-temperature molten salt tank 6. The working temperature of the high-temperature molten salt tank 5 can reach 565℃ or even higher, such as 700-750℃. The temperature of the low-temperature molten salt tank 6 is usually set above 210℃ and lower than the temperature of the molten salt in the high-temperature molten salt tank 5, to ensure that the molten salt is in a liquid state and can effectively exchange heat. The melting point of molten salt is usually around 210℃, so the temperature of the low-temperature molten salt tank 6 must be higher than the melting point to prevent the molten salt from solidifying.

[0024] The part of the oil-salt heat exchange tube in the moving fluidized bed 2 is designed in a continuous multi-segment curved serpentine shape, which can maximize the heat exchange area and improve the heat exchange efficiency. At the same time, the segment outside the moving fluidized bed 2 is coiled on the heat-removing pipeline, forming a compact layout. The oil-salt heat exchange tube is filled with heat-conducting oil, which acts as a heat transfer medium and can efficiently absorb and release heat.

[0025] The oil-salt heat exchange tube directly contacts the slag particles in the moving fluidized bed 2 to transfer the high-temperature sensible heat of the slag particles to the heat-conducting oil, which then transfers the heat to the low-temperature molten salt in the heat-removing pipeline, thereby realizing the heating process of the molten salt. The temperature of the liquid slag discharged from the blast furnace is about 1400℃-1500℃, and the heat-conducting oil fully exchanges heat with the hot molten slag particles in the moving fluidized bed 2, with a temperature of about 1100℃-1200℃ after heat exchange.

[0026] The upstream equipment of the moving fluidized bed 2 is a centrifugal granulator 1. Liquid slag enters the centrifugal granulator 1 from the inlet end, is broken into small slag particles by high-speed rotation of the centrifugal effect, and is sprayed from the outlet end directly to the moving fluidized bed 2. In this process, the liquid slag is broken into small slag particles with a size of 0.5-3 mm.

[0027] The moving fluidized bed 2 carries the slag particles sprayed from the centrifugal granulator 1 and makes the slag particles exchange heat with the oil-salt heat exchange pipe in a fluidized state. The downstream equipment of the moving fluidized bed 2 is a slag bin 3. The slag particles after heat exchange are discharged from the downstream of the moving fluidized bed 2 and enter the slag bin 3 for storage or further processing.

[0028] As shown in Figure 1 The superheater 8, the evaporator 9 and the preheater 10 arranged on the heat release pipeline are used as components of steam power generation. The superheater 8, the evaporator 9 and the preheater 10 are connected in sequence on the heat release pipeline and used to transfer the heat of high-temperature molten salt to steam to generate superheated steam. The superheated steam can meet the demand of the steam turbine 14 for high-quality steam.

[0029] The condenser 12 is connected to the steam pipeline and used to condense the exhaust steam discharged from the steam turbine 14 into water for recycling. The reheater 11 is connected to the steam turbine 14 and used to heat the steam extracted from the intermediate stage of the steam turbine 14 again to improve the thermal efficiency of the steam. The heat release branch pipe is connected to the heat release pipeline in parallel with the superheater 8 and used to provide heat for the reheater 11. One end of the heat release branch pipe is connected to the heat release pipeline between the outlet of the high-temperature molten salt tank 5 and the superheater 8, and the other end is connected to the heat release pipeline between the superheater 8 and the evaporator 9, so as to ensure that the reheater 11 can obtain sufficient heat.

[0030] It should be noted that the superheater 8, the evaporator 9 and the preheater 10 are connected in sequence on the heat release pipeline, and the steam flows through the preheater 10, the evaporator 9 and the superheater 8 in sequence. This specific arrangement sequence has a clear purpose and significant effect.

[0031] Specifically, the temperature of the steam gradually increases when it flows through these devices. The preheater 10 first makes the steam reach a certain initial temperature to prepare for the subsequent evaporation and superheating process. The evaporator 9 further heats the steam to a saturated state, i.e., the temperature of the steam is equal to the saturation temperature under its pressure. Finally, the superheater 8 heats the saturated steam into superheated steam, so that its temperature is higher than the saturation temperature, to meet the demand of the steam turbine 14 or other steam-using equipment for high-temperature steam.

[0032] This arrangement sequence helps to efficiently utilize heat energy. The high-temperature molten salt transfers heat to the steam through the heat release pipeline, and the temperature of the steam gradually increases, which means that the temperature change of the steam is more stable under the condition of transferring the same amount of heat, reducing the waste of heat energy.

[0033] The sequential arrangement of the preheater 10, the evaporator 9, and the superheater 8 also helps to protect the equipment. If the steam were to enter the superheater 8 directly without going through the preheating and evaporation processes, the superheater 8 might not work effectively due to the low temperature of the steam, or even be damaged due to the large temperature difference. In addition, the high temperature of the superheated steam can also preheat the steam turbine 14, reducing the thermal stress of the steam turbine 14 during startup.

[0034] Through the sequential heating of the preheater 10, the evaporator 9, and the superheater 8, the quality of the steam is significantly improved. The superheated steam has a higher temperature and pressure, which can better meet the needs of the steam turbine 14 or other steam-using equipment, improving the operating efficiency and stability of the equipment. This sequential arrangement makes the thermal system more flexible. By adjusting the heating power of the preheater 10, the evaporator 9, and the superheater 8, the temperature and pressure of the steam can be easily controlled to meet the needs of different working conditions. Since the thermal energy is efficiently utilized, the energy consumption of the entire thermal system is reduced. At the same time, since the quality of the steam is improved, the operating efficiency of the steam turbine 14 or other steam-using equipment is also improved, further reducing energy consumption.

[0035] The output end of the steam turbine 14 is connected to the generator 13, converting mechanical energy into electrical energy, achieving efficient utilization of energy. The electrical energy generated by the generator 13 is used to drive the electric heating device 7, assisting in heating or maintaining the temperature stability of the molten salt in the high-temperature molten salt tank 5. The high-temperature molten salt tank 5 is also equipped with an electric heating device 7, which can accommodate green electricity and valley electricity, and balance the energy consumption of the metallurgical and chemical enterprise through the energy management system, increasing the efficiency of the enterprise.

[0036] Through the serpentine design of the oil-salt heat exchange pipe and the filling of the heat-conducting oil, the heat exchange efficiency is significantly improved, making the heating process of the molten salt more efficient. Through the sequential arrangement of the superheater 8, the evaporator 9, and the preheater 10, as well as the use of the reheater 11, the quality of the steam is optimized to meet the needs of the steam turbine 14 for high-quality steam. The exhaust steam discharged by the steam turbine 14 is condensed into water by the condenser 12 and recycled; at the same time, the electrical energy generated by the generator 13 is used in part for the electric heating device 7, achieving the recycling of energy. Through the compact layout and optimized connection of equipment, the complexity of the system is reduced, and the stability and reliability of the system are improved.

[0037] In addition, in the present embodiment, a yellow phosphorus plant with an annual output of 600,000 tons of yellow phosphorus is taken as an example, the annual electricity consumption is 1 billion degrees of electricity, the annual output of slag is 600,000 tons, and the slag temperature is more than 1400 degrees Celsius. The slag is discharged once every 3 hours or so, the slag discharge time of a 12.5 MW furnace is about 45 minutes, the slag discharge amount is about 30 t, the slag discharge time of a 25 MW furnace is about 45-60 minutes, the slag discharge amount is about 60 t; under normal circumstances, 1800 t per day (8 electric furnaces are in production). At present, due to the influence of limited electricity and other factors, the daily slag discharge amount is 1400 t per day (5 electric furnaces are in production).

[0038] The liquid molten slag recovery and storage system based on molten salt energy storage provided in the present embodiment is provided with one set of liquid molten slag recovery and storage system based on molten salt energy storage for each furnace, the molten slag is granulated by the centrifugal granulator 1 and the activity degree of the granulated slag is maintained, the waste heat after the molten slag is granulated is recovered by the oil-salt heat exchanger 4, steam is generated, and the continuous and stable steam is output for production through waste heat recovery control. In view of the fact that 8 furnaces are in production on site, the production cycle is 3 hours of smelting and 45-60 minutes of slag discharge, therefore, the waste heat system also cooperates with the production scheduling system to adjust the slag discharge of 2 furnaces each time, the operation is continuous slag discharge in form, and the stable steam output can be realized in combination with the waste heat recovery control.

[0039] The generated steam is used for the production process of yellow phosphorus refining or phosphorus mud treatment, if there is surplus, it can be combined with boiler steam power generation or new independent power generation device to convert into electric energy for use.

[0040] The molten slag is discharged at 1400 degrees, the slag discharge temperature is 100 degrees, the water temperature is 20 degrees, the waste heat recovery rate is calculated at 80%, the total heat recoverable per ton of molten slag is about (460.8+1.1X1300)X1000X0.8=370070 kJ, about 136 kg of steam can be generated according to 1.25 MPa saturated steam, about 10.2 tons of steam can be generated according to the average of 75 t of molten slag per day, about 8.16 million tons of steam can be generated per year according to 60 million tons of slag per year; the total heat recovered is about 7576 tons of standard coal, and 1.8 million tons of CO2 is reduced; if the waste heat recovery rate is optimized to 90% during the design process, the average steam amount is about 11.475 tons, about 9.18 million tons of steam can be generated per year according to 60 million tons of slag per year; the total heat recovered is about 8523 tons of standard coal, and 2.1 million tons of CO2 is reduced; compared with the traditional water quenching method, the above molten slag waste heat recovery does not contain water, so it does not need to be dried when used externally, and therefore the external selling price can be increased to increase the additional income of the enterprise; if the waste heat recovery is implemented for all 8 furnaces, the original slag flushing water vapor recovery system and slag flushing will not be operated, and the overall energy consumption is further reduced.

[0041] The specific embodiments of the utility model have been described in detail above, but it only serves as an example, and the utility model is not limited to the specific embodiments described above. Any equivalent modification or alternative to the utility model made by those skilled in the art is also within the scope of the utility model, therefore, equivalent transformation, modification, improvement, etc. made without departing from the spirit and principle range of the utility model should be covered within the scope of the utility model.

Claims

1. A liquid slag recovery storage system based on molten salt energy storage, characterized in that, The application relates to a molten salt heat exchange system, which comprises a high-temperature molten salt tank and a low-temperature molten salt tank, the outlet of the low-temperature molten salt tank is connected to the inlet of the high-temperature molten salt tank through a heat extraction pipeline, an oil-salt heat exchanger is arranged on the heat extraction pipeline and heat exchange is formed, the oil-salt heat exchange pipeline of the oil-salt heat exchanger extends to a mobile fluidized bed, the mobile fluidized bed carries slag particles after liquid molten slag is broken and granulated, the oil-salt heat exchange pipeline exchanges heat with the slag particles, the outlet of the high-temperature molten salt tank is connected to the inlet of the low-temperature molten salt tank through a heat release pipeline, a superheater, an evaporator and a preheater are sequentially arranged on the heat release pipeline and heat exchange is formed between the heat release pipeline and the superheater, the evaporator and the preheater respectively, and an electric heating device is arranged on the high-temperature molten salt tank.

2. The molten-salt energy-based, liquid slag recovery storage system of claim 1, wherein, The segment of the oil-salt heat exchange pipeline in the mobile fluidized bed is continuously and multi-segmentally curved in a serpentine shape, the segment outside the mobile fluidized bed is coiled on the heat extraction pipeline, and the oil-salt heat exchange pipeline is filled with heat-conducting oil.

3. The molten-salt energy-storage-based liquid slag recovery storage system of claim 1 or 2, wherein, A centrifugal granulator is connected to the upstream of the mobile fluidized bed, the inlet end of the centrifugal granulator is connected to liquid molten slag, the outlet of the centrifugal granulator is directed to the mobile fluidized bed, and a slag bin is connected to the downstream of the mobile fluidized bed.

4. The molten-salt energy-based liquid slag recovery storage system of claim 1, wherein, The superheater, the evaporator and the preheater are connected to a steam pipeline of a steam turbine, and a condenser is further arranged on the steam pipeline.

5. The molten-salt energy-based liquid slag recovery storage system of claim 4, wherein, The steam turbine is further connected to a reheater, the heat release pipeline is connected to a heat release branch pipeline parallel to the superheater, and the reheater exchanges heat with the heat release branch pipeline.

6. The molten-salt energy-based liquid slag recovery storage system of claim 5, wherein, One end of the heat release branch pipeline is connected to the heat release pipeline between the superheater and the outlet of the high-temperature molten salt tank, and the other end of the heat release branch pipeline is connected to the heat release pipeline between the superheater and the evaporator.

7. The molten-salt energy-based liquid slag recovery storage system of claim 5, wherein, The output end of the steam turbine is connected to a generator, and the generator is connected to the electric heating device.

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