Aluminum-silicon flue gas waste heat cooperative power generation system and energy saving method

Abstract

The invention relates to the technical field of flue gas waste heat recovery, and provides an aluminum-silicon flue gas waste heat cooperative power generation system and an energy saving method.The system comprises a gas-water heat exchanger, a hot water pump, a waste heat boiler, a steam turbine, a power generator, a condenser, a circulating water pump, an aluminum electrolysis cell group, an ore-smelting electric furnace group, a dust removal system and a flue gas purification system; the aluminum electrolysis cell group is connected with the gas-water heat exchanger; hot water subjected to heat exchange of the gas-water heat exchanger is pumped into a deaerator through a hot water pump to be deoxidized and then enters a waste heat boiler, high-temperature flue gas of the ore-smelting electric furnace group is introduced into the waste heat boiler to heat the hot water, and then the hot water is discharged after being treated by a dust removal system; high-temperature steam generated by the waste heat boiler enters the steam turbine, and the steam turbine is matched with the power generator to generate power; after being condensed by the condenser, steam discharged by the steam turbine enters the gas-water heat exchanger through the circulating water pump for water replenishing and heat exchange. The system saves energy and reduces consumption, waste heat waste is reduced, greenhouse gas emission is reduced, and the requirement for green and low-carbon production is met.

Description

Technical Field

[0001] The present application belongs to the technical field of flue gas waste heat recovery, and more specifically, relates to an aluminum-silicon flue gas waste heat collaborative power generation system and an energy-saving method. Background Art

[0002] A large amount of low-temperature flue gas is generated during the production of electrolytic aluminum, and the temperature usually does not exceed 140°C. Although it has abundant waste heat resources, the efficiency of power generation using conventional technology is low. In addition, affected by the continuous rise in natural gas prices, power generation based on natural gas supplementary combustion has gradually lost its economic advantage. In comparison, the flue gas temperature of silicon plants is usually between 470°C and 550°C, which belongs to the medium and high temperature range and is more suitable for waste heat power generation. At present, the technologies for the utilization of waste heat from low-temperature flue gas include low-temperature economizers, absorption refrigeration, and low-temperature thermoelectric conversion technologies; while the utilization of waste heat from high-temperature flue gas mostly adopts various power cycle recovery technologies. However, the existing waste heat utilization schemes are mostly designed for single factory conditions, and lack systematic solutions for cross-factory collaborative utilization. In industrial parks, since multiple factories are usually distributed adjacent to each other, it is of great research value to realize the collaborative utilization of waste heat among multiple factories to improve the overall energy utilization efficiency. Summary of the invention

[0003] In response to the problems existing in the above-mentioned prior art, the purpose of the embodiments of the present application is to provide an aluminum-silicon flue gas waste heat collaborative power generation system, which realizes the efficient and comprehensive utilization of flue gas waste heat at different temperatures by transporting the low-temperature flue gas waste heat from the aluminum plant to the silicon plant and combining it with the high-temperature flue gas waste heat resources of the silicon plant for joint power generation.

[0004] To achieve the above purpose, the technical solution adopted in this application is: to provide an aluminum-silicon flue gas waste heat coordinated power generation system, including: an air-water heat exchanger, a hot water pump, a waste heat boiler, a steam turbine, a generator, a condenser, a circulating water pump, a dust removal system, an aluminum electrolytic cell group, a flue gas purification system and a mineral thermal electric furnace group; The low-temperature flue gas generated by the aluminum electrolysis cell group is subjected to heat exchange in the air-water heat exchanger and then enters the flue gas purification system for treatment before being discharged; The hot water generated after heat exchange in the gas-water heat exchanger is pumped into the deaerator through a hot water pump for deoxygenation, and then enters the waste heat boiler. The high-temperature flue gas generated by the electric furnace group is introduced into the waste heat boiler to heat the hot water, and then discharged after being treated by the dust removal system; The high-temperature steam generated by the waste heat boiler enters the steam turbine, and the steam turbine cooperates with the generator to generate electricity; The steam exhausted from the steam turbine is condensed by the condenser and then re-enters the air-water heat exchanger through a circulating water pump for heat exchange.

[0005] In one embodiment, the deaerator is a thermal deaerator.

[0006] In one embodiment, the dust removal system is connected to a fume exhaust system.

[0007] In one embodiment, the flue gas purification system is connected to a smoke exhaust system.

[0008] In one embodiment, the gas-water heat exchanger is used to transfer the heat of the low-temperature flue gas to the water body to produce high-temperature hot water with a temperature of 110-125° C. and a pressure of 0.2-0.4 MPa.

[0009] In one embodiment, the waste heat boiler is used to receive hot water deoxygenated by the deaerator and generate high-temperature and high-pressure steam, with a steam temperature of 430-445° C. and a pressure of 3.3-3.45 MPa.

[0010] In one embodiment, the water inlet of the air-water heat exchanger is connected to an external raw water pipeline, and the circulating water pump pressurizes the condensed water and transports it back to the air-water heat exchanger through the raw water pipeline to achieve water recycling.

[0011] In one embodiment, the air-water heat exchanger is a liquid flow heat exchanger.

[0012] Another object of the present application is to provide an energy-saving method based on the aluminum-silicon flue gas waste heat coordinated power generation system as described above, comprising the following steps: S1. The flue gas generated by electrolytic aluminum in the aluminum plant is transported to the air-water heat exchanger through the flue gas pipeline. The flue gas with greatly reduced heat after passing through the air-water heat exchanger is discharged through the flue gas purification system to ensure that the flue gas discharged into the atmosphere meets environmental protection requirements; S2, the air-water heat exchanger manufactures high-temperature hot water with a temperature of 110-125°C and a pressure of 0.2-0.4MPa, which is then pumped to the deaerator in front of the waste heat boiler of the silicon plant for deoxidation treatment; S3, the deoxygenated hot water is then fed into the waste heat boiler through the boiler medium-pressure feed water pump to generate superheated steam with a temperature of 430-445°C and a pressure of 3.3-3.45MPa; S4, then use the steam to drive the generator to generate electricity through the steam turbine, converting the mechanical energy into electrical energy; S5. The steam exhausted from the steam turbine is cooled into water through the condenser, and then circulated back to the air-water heat exchanger through the circulating water pump for recycling.

[0013] The beneficial effects of the aluminum-silicon flue gas waste heat coordinated power generation system and energy-saving method provided in this application are: 1. By transporting the low-temperature flue gas waste heat from the aluminum plant to the silicon plant and combining it with the high-temperature flue gas waste heat resources of the silicon plant for joint power generation, efficient and comprehensive utilization of flue gas waste heat at different temperatures can be achieved. The system design strictly follows the principles of "energy use according to quality" and "maximum use of heat", optimizes the waste heat utilization process, and aims to improve the energy utilization rate of low-temperature, medium-temperature and high-temperature flue gas, and significantly improve the overall waste heat power generation efficiency. At the same time, the system effectively solves the problem of low efficiency of low-temperature waste heat power generation in a single aluminum plant, and provides a feasible path for industrial energy conservation and emission reduction.

[0014] 2. Through this collaborative power generation system, the efficiency of waste heat utilization can be greatly improved, the energy consumption and operating costs of enterprises can be reduced, and the greenhouse gas content in flue gas emissions can be reduced, which meets the requirements of green and low-carbon production. This collaborative power generation system integrates the waste heat resources of aluminum plants and silicon plants to build an aluminum-silicon flue gas waste heat collaborative power generation system and energy-saving method, aiming to effectively solve the problem of insufficient utilization of existing waste heat resources and provide innovative technical means for the efficient utilization of waste heat in the industrial field.

[0015] 3. Use part of the flue gas from the aluminum plant to produce high-temperature hot water with a temperature of 110-125°C and a pressure of 0.2-0.4MPa through an air-water heat exchanger, and send it to the thermal deaerator in front of the waste heat boiler of the silicon plant. Then, it is sent to the waste heat boiler through the boiler medium-pressure feed water pump to generate superheated steam with a temperature of 430-445°C and a pressure of 3.3-3.45MPa. The steam turbine drives the generator to generate electricity, with considerable power generation.

[0016] 4. Due to the huge flow of low-temperature flue gas from the aluminum plant, it can not only meet the waste heat sent to the silicon plant for joint power generation, so that the silicon plant's ore-fired electric furnace can work 1 to 2 more units, but also have a surplus of 7 to 8MW of electricity returned to the aluminum plant for use, meeting part of its own electricity needs.

[0017] 5. In silicon plants, waste heat boilers are used to supply steam to the silicon plants (near the medium frequency furnaces), which can replace the original electric boiler system and save costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A schematic diagram of the connection relationship of the aluminum-silicon flue gas waste heat collaborative power generation system provided in an embodiment of the present application.

[0020] Among them, the reference numerals in the figure are: 1. Air-water heat exchanger; 2. Smoke exhaust system; 3. Hot water pump; 4. Deaerator; 5. Waste heat boiler; 6. Steam turbine; 7. Generator; 8. Condenser; 9. Circulating water pump; 10. Dust removal system; 11. Aluminum electrolytic cell group; 12. Flue gas purification system; 13. Submersible thermal electric furnace group. DETAILED DESCRIPTION

[0021] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0022] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0023] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0024] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0025] like Figure 1 As shown, an aluminum-silicon flue gas waste heat coordinated power generation system provided in an embodiment of the present application is now described. The aluminum-silicon flue gas waste heat coordinated power generation system includes: an air-water heat exchanger 1, a smoke exhaust system 2, a hot water pump 3, a deaerator 4, a waste heat boiler 5, a steam turbine 6, a generator 7, a condenser 8, a circulating water pump 9, a dust removal system 10, an aluminum electrolytic cell group 11, a flue gas purification system 12, and a mineral thermal electric furnace group 13.

[0026] Among them, the air inlet of the air-water heat exchanger 1 is connected to the exhaust port of the aluminum electrolytic cell group 11, receiving the low-temperature flue gas generated by the aluminum electrolysis in the aluminum plant; the water inlet of the air-water heat exchanger 1 is connected to the external raw water pipeline, and the circulating water pump returns water to the raw water pipeline to replenish the raw water, and then flows into the air-water heat exchanger 1 for water recycling. The water outlet of the air-water heat exchanger 1 is connected to the water inlet of the hot water pump 3 through a pipeline to transfer heat to the water body and send the heated hot water to subsequent equipment; and the low-temperature flue gas generated by the aluminum electrolytic cell group 11 enters the flue gas purification system 12 for treatment and discharge after heat exchange through the air-water heat exchanger 1.

[0027] Among them, the water inlet of the hot water pump 3 is connected to the water outlet of the air-water heat exchanger 1 to receive hot water; the water outlet of the hot water pump 3 is connected to the water inlet of the deaerator 4 to transport the hot water to the deaerator 4 for deoxygenation. The water outlet of the deaerator 4 is connected to the specific water inlet of the waste heat boiler 5 to transport the deoxygenated hot water to the waste heat boiler 5 to ensure the quality of the water in the boiler and avoid oxygen corrosion. The air inlet of the waste heat boiler 5 is adjacent to the exhaust pipe of the mine heat circuit group 13 to absorb the heat energy of its high-temperature flue gas. The water outlet of the waste heat boiler 5 is connected to the steam turbine 6 to transport the generated high-temperature and high-pressure steam to the steam turbine 6 to drive the steam turbine 6 to rotate. When the steam turbine 6 rotates, it drives the generator 7 to work and generate electricity, thereby realizing the conversion of thermal energy to mechanical energy, and then converting the mechanical energy into electrical energy; the air outlet of the waste heat boiler 5 is connected to the air inlet of the dust removal system 10 to remove dust from the flue gas.

[0028] Among them, the air inlet of the condenser 8 is connected to the air outlet of the turbine 6 to receive the steam exhausted from the turbine 6; the water outlet of the condenser 8 is connected to the water inlet of the circulating water pump 9 to condense the steam into water through cooling, and the water inlet of the circulating water pump 9 is connected to the water outlet of the condenser 8 to receive the condensed water; the water outlet of the circulating water pump 9 is connected to the raw water pipeline to re-pressurize the condensed water and transport it to the air-water heat exchanger 1 through the raw water pipeline for recycling.

[0029] In this embodiment, the air outlet of the dust removal system 10 is connected to the air inlet of the smoke exhaust system 2, and the smoke is dusted before being discharged; the smoke after dust removal is transported to the smoke exhaust system 2 for discharge, ensuring that the smoke discharged into the atmosphere meets environmental protection requirements. The air outlet of the smoke purification system 12 is connected to the air inlet of the smoke exhaust system 2, and the smoke is purified before being discharged, and the purified smoke is transported to the smoke exhaust system 2 for discharge, ensuring that the smoke discharged into the atmosphere meets environmental protection requirements.

[0030] In this embodiment, the deaerator 4 is a thermal deaerator, and the gas-water heat exchanger 1 is a liquid flow heat exchanger. The gas-water heat exchanger 1 is used to transfer the heat of the low-temperature flue gas to the water body, and produce high-temperature hot water with a temperature of 110-125°C and a pressure of 0.2-0.4MPa; the waste heat boiler 5 is used to receive the hot water after deoxygenation by the deaerator 4, and generate high-temperature and high-pressure steam, with a steam temperature of 430-445°C and a pressure of 3.3-3.45Mpa.

[0031] In this embodiment, an energy-saving method based on the above-mentioned aluminum-silicon flue gas waste heat coordinated power generation system is also provided, and the energy-saving method comprises the following steps: S1. First, the low-temperature flue gas generated by the aluminum electrolytic cell group 11 in the aluminum plant during the electrolytic aluminum production is transported to the air-water heat exchanger 1 through the flue gas pipeline for heat exchange. The flue gas with greatly reduced heat after heat exchange in the air-water heat exchanger 1 is discharged through the flue gas purification system 12. The gas outlet of the flue gas purification system 12 is connected to the air inlet of the exhaust system 2 to remove fluorides, acidic gases, and nitrogen oxides in the dust. Through these treatments, the impact on the environment during the electrolytic aluminum production process can be effectively reduced and the air quality can be protected. The purified flue gas is transported to the exhaust system 2 for discharge to ensure that the flue gas discharged into the atmosphere meets environmental protection requirements.

[0032] S2. The air-water heat exchanger 1 manufactures high-temperature hot water with a temperature of 110-125°C and a pressure of 0.2-0.4MPa, and then sends it to the deaerator 4 in front of the waste heat boiler 5 of the silicon plant through the hot water pump 3 for deoxygenation treatment; this is the embodiment of the air-water heat exchanger 1 realizing heat transfer to the water body. Its water inlet is connected to the raw water or water supply source, and the water outlet is connected to the water inlet of the hot water pump 3, which can send the heated water to the subsequent equipment. Then it is sent to the thermal deaerator 4 in front of the waste heat boiler 5 of the silicon plant through the hot water pump 3. In the device, the water outlet of the hot water pump 3 is connected to the water inlet of the deaerator 4, receiving hot water and transporting it to the deaerator 4 for deoxygenation treatment, and the deaerator 4 can effectively remove oxygen in the water to prevent corrosion inside the boiler.

[0033] S3. The deoxygenated hot water is then fed into the waste heat boiler 5 through the feed water pump in the boiler to generate superheated steam with a temperature range of 430°C to 445°C and a pressure range of 3.3 to 3.45 MPa. The water outlet of the deaerator 4 is connected to the specific water inlet of the waste heat boiler 5 to transport the deoxygenated hot water to the waste heat boiler 5. The waste heat boiler 5 is connected to the water outlet of the deaerator 4 on the one hand to ensure sufficient hot water supply, and is connected to the mineral heat electric furnace group 13 on the other hand to absorb heat from the high-temperature flue gas generated by the mineral heat circuit group. The steam generated by the waste heat boiler 5 can be supplied to the silicon plant for power generation to utilize the waste heat, thereby realizing the power supply to the silicon plant, thereby replacing the traditional electric boiler system.

[0034] S4. Then, the steam is used to drive the generator 7 through the steam turbine 6 to generate electricity, converting the thermal energy into mechanical energy, and then converting the mechanical energy into electrical energy; the air inlet of the steam turbine 6 is connected to the air outlet of the waste heat boiler 5, and the shaft of the steam turbine 6 that receives the high-temperature and high-pressure steam is connected to the shaft of the generator 7. The steam drives the steam turbine 6 to rotate, and then drives the generator 7 to rotate, converting the mechanical energy into electrical energy.

[0035] S5. The steam exhausted from the steam turbine 6 is cooled into water through the condenser 8. The air inlet of the condenser 8 is connected to the air outlet of the steam turbine 6, and receives the steam exhausted from the steam turbine 6. The water outlet of the condenser 8 is connected to the water inlet of the circulating water pump 9, and the steam is condensed into water through cooling, and the condensed water is transported to the circulating water pump 9. Then the circulating water pump 9 circulates the condensed water back to the air-water heat exchanger 1, and the air-water heat exchanger 1 is replenished with water to realize recycling and reduce the consumption of raw water resources.

[0036] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. An aluminum-silicon flue gas waste heat synergistic power generation system, characterized in that: include: Gas-water heat exchanger (1), hot water pump (3), deaerator (4), waste heat boiler (5), steam turbine (6), generator (7), condenser (8), circulating water pump (9), dust removal system (10), aluminum electrolytic cell group (11), flue gas purification system (12) and ore-fired electric furnace group (13); The low-temperature flue gas generated by the aluminum electrolysis cell group (11) passes through the gas-water heat exchanger (1) for heat exchange, then enters the flue gas purification system (12) for treatment and then is discharged; The hot water generated after heat exchange in the gas-water heat exchanger (1) is pumped into the deaerator (4) through a hot water pump (3) for deoxygenation, and then enters the waste heat boiler (5); the high-temperature flue gas generated by the electric furnace group (13) is introduced into the waste heat boiler (5) to heat the hot water, and then discharged after being processed by the dust removal system (10); The high-temperature steam generated by the waste heat boiler (5) enters the steam turbine (6), and the steam turbine (6) cooperates with the generator (7) to generate electricity; The steam exhausted from the steam turbine (6) is condensed by the condenser (8) and then re-enters the gas-water heat exchanger (1) through a circulating water pump (9) for heat exchange.

2. The aluminum-silicon flue gas waste heat coordinated power generation system according to claim 1, characterized in that: The deaerator (4) is a thermal deaerator.

3. The aluminum-silicon flue gas waste heat coordinated power generation system according to claim 2, characterized in that: The dust removal system (10) is connected to a smoke exhaust system (2).

4. The aluminum-silicon flue gas waste heat coordinated power generation system according to claim 3, characterized in that: The flue gas purification system (12) is connected to a smoke exhaust system (2).

5. The aluminum-silicon flue gas waste heat coordinated power generation system according to claim 4, characterized in that: The gas-water heat exchanger (1) is used to transfer the heat of the low-temperature flue gas to the water body, thereby producing high-temperature hot water with a temperature of 110 to 125° C. and a pressure of 0.2 to 0.4 MPa.

6. The aluminum-silicon flue gas waste heat coordinated power generation system according to claim 5, characterized in that: The waste heat boiler (5) is used to receive the hot water after being deoxygenated by the deaerator (4) and generate high-temperature and high-pressure steam, wherein the steam temperature is 430 to 445° C. and the pressure is 3.3 to 3.45 MPa.

7. The aluminum-silicon flue gas waste heat coordinated power generation system according to claim 6, characterized in that: The water inlet of the air-water heat exchanger (1) is connected to an external raw water pipeline, and the circulating water pump (9) pressurizes the condensed water and transports it back to the air-water heat exchanger (1) through the raw water pipeline, thereby realizing the recycling of water.

8. The aluminum-silicon flue gas waste heat coordinated power generation system according to claim 6, characterized in that: The gas-water heat exchanger (1) is a liquid flow heat exchanger.

9. An energy-saving method based on the aluminum-silicon flue gas waste heat coordinated power generation system according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. The flue gas generated by the electrolytic aluminum of the aluminum plant is transported to the air-water heat exchanger (1) through the flue gas pipeline. After passing through the air-water heat exchanger (1), the flue gas with greatly reduced heat is discharged through the flue gas purification system (12), ensuring that the flue gas discharged into the atmosphere meets environmental protection requirements; S2, the air-water heat exchanger (1) produces high-temperature hot water with a temperature of 110-125°C and a pressure of 0.2-0.4 MPa, and then sends it to the deaerator (4) in front of the waste heat boiler (5) of the silicon plant through a hot water pump (3) for deoxidation treatment; S3, the deoxygenated hot water is then fed into the waste heat boiler (5) through the boiler medium-pressure feed water pump to generate superheated steam with a temperature of 430-445°C and a pressure of 3.3-3.45 MPa; S4, then using steam to drive a generator (7) to generate electricity through a steam turbine (6), thereby converting mechanical energy into electrical energy; S5. The steam exhausted from the steam turbine (6) is cooled into water through the condenser (8), and then circulated back to the air-water heat exchanger (1) through the circulating water pump (9) for recycling.

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