System and method for utilizing waste heat of silicon plant and aluminum plant

Abstract

The invention relates to the technical field of energy recovery and utilization, in particular to a system and method combining waste heat utilization of a silicon plant and an aluminum plant. The system comprises an aluminum factory flue gas output device, a gas-water heat exchanger, a silicon factory ore-smelting electric furnace, a waste heat boiler, a steam turbine and a generator. A gas inlet of the gas-water heat exchanger is connected to a gas outlet of a smoke output device of an aluminum factory, a water inlet of the waste heat boiler is connected to a water outlet of the gas-water heat exchanger, a gas inlet of the waste heat boiler is connected to a gas outlet of an ore-smelting electric furnace of a silicon factory, a steam inlet of the steam turbine is connected to a steam outlet of the waste heat boiler, and the steam turbine is connected to the generator. The gas-water heat exchanger is used for recycling heat in electrolytic aluminum flue gas of an aluminum factory to form hot water; the waste heat boiler is used for recycling heat in smoke of the electric furnace to form steam, and the steam is used for doing work in the steam turbine to enable the generator to generate electricity. According to the scheme, waste heat loss of an aluminum factory can be reduced, waste heat power generation benefits are improved, and therefore the purpose of saving energy is achieved.

Description

Technical Field

[0001] The present application relates to the technical field of energy recovery and utilization, and in particular to a system and method for utilizing waste heat from silicon and aluminum plants. Background Art

[0002] There is a large amount of low-temperature flue gas in electrolytic aluminum, but the flue gas temperature is usually low. The total flow is very large, resulting in abundant waste heat resources, but it is difficult to directly generate electricity using conventional methods. With the continuous rise in natural gas prices, the economic benefits of using natural gas supplementary combustion to generate electricity are not significant. For the silicon plant next door, the flue gas flow of the submerged thermal electric furnace is lower than that of the aluminum plant, and the flue gas temperature is relatively high, which is suitable for waste heat power generation.

[0003] In order to reduce the energy consumption of enterprises, save costs, and reduce the thermal pollution caused by waste heat and exhaust gas to the surrounding environment, the present invention designs a waste heat utilization system for aluminum and silicon plants, which can reduce the waste heat loss of the aluminum plants and improve the efficiency of waste heat power generation, thereby achieving the purpose of saving energy. Summary of the invention

[0004] The embodiments of the present application at least provide a system and method for utilizing waste heat from silicon and aluminum plants, which can reduce waste heat losses in the aluminum plant and improve the efficiency of waste heat power generation, thereby achieving the purpose of saving energy.

[0005] In the first aspect, the embodiment of the present application provides a system for utilizing waste heat from two silicon and aluminum plants, including: a flue gas output device of the aluminum plant, an air-water heat exchanger, a first tail gas emission unit, a silicon plant ore-fired thermal electric furnace, a waste heat boiler, a second tail gas emission unit, a steam turbine and a generator;

[0006] The aluminum plant fume output device is used to discharge the aluminum electrolytic aluminum fume of the aluminum plant;

[0007] The air inlet of the air-water heat exchanger is connected to the air outlet of the aluminum plant fume output device, and is used to recover the heat in the aluminum electrolysis fume of the aluminum plant to form hot water;

[0008] The air inlet of the first tail gas discharge unit is connected to the air outlet of the air-water heat exchanger, and is used to discharge the tail gas of the air-water heat exchanger;

[0009] The silicon plant thermal furnace is used to burn and generate thermal furnace flue gas;

[0010] The water inlet of the waste heat boiler is connected to the water outlet of the gas-water heat exchanger, and the air inlet of the waste heat boiler is connected to the air outlet of the thermal electric furnace of the silicon plant, so as to recover the heat in the flue gas of the thermal electric furnace to form high-temperature and high-pressure steam;

[0011] The air inlet of the second tail gas discharge unit is connected to the air outlet of the waste heat boiler, and is used to discharge the tail gas of the waste heat boiler;

[0012] The steam inlet of the steam turbine is connected to the steam outlet of the waste heat boiler, and is used to convert the thermal energy of the high-temperature and high-pressure steam into mechanical energy to drive the generator to generate electricity.

[0013] In an optional embodiment, the hot water has a temperature of 125° C. and a pressure of 0.35-0.4 MPa.

[0014] In an optional embodiment, the high-temperature and high-pressure steam has a temperature of 450°C and a pressure of 3.82 MPa.

[0015] In an optional implementation, a hot water pump is provided between the gas-water heat exchanger and the waste heat boiler.

[0016] In an optional embodiment, a deaerator is provided between the waste heat boiler and the gas-water heat exchanger.

[0017] In an optional embodiment, the water outlet of the steam turbine is connected to a hot water pipe, and the hot water pipe is used to supply water to the water-using end.

[0018] In an optional embodiment, the water outlet of the steam turbine is connected to the water inlet of the air-water heat exchanger through a condenser.

[0019] In an optional embodiment, a booster pump is provided between the steam turbine and the gas-water heat exchanger.

[0020] In an optional embodiment, the first tail gas emission unit and the second tail gas emission unit both include a flue gas purification device.

[0021] In a second aspect, the embodiment of the present application further provides a method for utilizing waste heat from two silicon and aluminum plants, which is applicable to the system for utilizing waste heat from two silicon and aluminum plants in the first aspect, including:

[0022] The aluminum plant fume output device discharges the aluminum plant electrolytic aluminum fume into the air-water heat exchanger, and the air-water heat exchanger recovers the heat in the aluminum plant electrolytic aluminum fume to form hot water;

[0023] The silicon plant thermal furnace discharges the generated thermal furnace flue gas into the waste heat boiler, and the waste heat boiler recovers the heat in the thermal furnace flue gas to heat the hot water to form high-temperature and high-pressure steam;

[0024] The steam turbine converts the thermal energy of high-temperature and high-pressure steam into mechanical energy to drive the generator to generate electricity.

[0025] The above technical solution of the present application has the following beneficial technical effects:

[0026] The system for utilizing waste heat from both silicon and aluminum plants in the embodiment of the present application can respectively recover heat from the flue gas of aluminum electrolysis and the flue gas of the thermal electric furnace of the silicon plant for power generation. This can reduce waste heat losses from the aluminum plant on the one hand, and improve the efficiency of waste heat power generation on the other hand, thereby achieving the goal of saving energy.

[0027] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. The drawings herein are incorporated into the specification and constitute a part of the specification. These drawings illustrate embodiments consistent with the present application and are used together with the specification to illustrate the technical solutions of the present application. It should be understood that the following drawings only illustrate certain embodiments of the present application and should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can also be obtained based on these drawings without creative work.

[0029] Figure 1 A schematic diagram of a system for utilizing waste heat from two silicon and aluminum plants provided in an embodiment of the present application is shown;

[0030] Figure 2 A schematic diagram of the structure of a system for utilizing waste heat from silicon and aluminum plants provided in an embodiment of the present application is shown;

[0031] Reference numerals:

[0032] 1. Air-water heat exchanger; 2. Flue gas purification system; 3. First flue gas exhaust boiler; 4. Hot water pump; 5. Deaerator; 6. Waste heat boiler; 7. Steam turbine; 8. Generator; 9. Condenser; 10. Booster pump; 11. Dust removal system; 12. Second flue gas exhaust boiler; 13. Flue gas output device; 14. Submersible thermal electric furnace. DETAILED DESCRIPTION

[0033] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0034] The embodiments of the present application will be described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as limitations on the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0035] The term "first" or "second" in the specification and claims of this application may include one or more of the features explicitly or implicitly. In the description of this application, unless otherwise specified, "plurality" means two or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / " generally means that the objects connected before and after are in an "or" relationship.

[0036] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element 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.

[0037] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0038] refer to Figure 1 and Figure 2The embodiment of the present application provides a system for utilizing waste heat from silicon and aluminum plants, including: an aluminum plant flue gas output device 13, an air-water heat exchanger 1, a silicon plant thermal electric furnace 14, a waste heat boiler 6, a steam turbine 7, and a generator 8. The aluminum plant flue gas output device 13 is used to discharge the aluminum electrolytic aluminum flue gas of the aluminum plant. The air inlet of the air-water heat exchanger 1 is connected to the air outlet of the aluminum plant flue gas output device 13, and is used to recover the heat in the aluminum electrolytic aluminum flue gas to form hot water. The silicon plant thermal electric furnace 14 is used to burn and generate thermal electric furnace flue gas. The water inlet of the waste heat boiler 6 is connected to the water outlet of the air-water heat exchanger 1, and the air inlet of the waste heat boiler 6 is connected to the air outlet of the silicon plant thermal electric furnace 14, and is used to recover the heat in the thermal electric furnace flue gas to form high-temperature and high-pressure steam. The steam inlet of the steam turbine 7 is connected to the steam outlet of the waste heat boiler 6, and is used to convert the thermal energy of the high-temperature and high-pressure steam into mechanical energy to drive the generator 8 to generate electricity.

[0039] Specifically, the system includes two waste heat recovery units and a power generation unit, wherein one waste heat recovery unit (gas-water heat exchanger 1) is used to recover heat from the low-temperature flue gas of the aluminum plant to form hot water from the low-temperature water, and the hot water flows to another waste heat recovery unit (waste heat boiler 6), and the other waste heat recovery unit is used to recover heat from the high-temperature flue gas to form high-temperature and high-pressure steam from the hot water. Finally, the high-temperature and high-pressure steam can work to drive the steam turbine 7 to rotate, and then drive the generator 8 to rotate, converting mechanical energy into electrical energy. In specific settings, the above two waste heat recovery units can be set in the aluminum plant and the silicon plant respectively.

[0040] In some embodiments, the aluminum plant fume output device 13 may be composed of a pipe.

[0041] In some embodiments, a hot water pump 4 is provided between the gas-water heat exchanger 1 and the waste heat boiler 6. Specifically, the water inlet of the hot water pump 4 is connected to the water outlet of the gas-water heat exchanger 1, and the water outlet of the hot water pump 4 is connected to the water inlet of the waste heat boiler 6. During use, the hot water pump 4 can pressurize the hot water to deliver the hot water to the waste heat boiler 6.

[0042] In some embodiments, a deaerator 5 is provided between the waste heat boiler 6 and the gas-water heat exchanger 1. Specifically, the deaerator 5 is provided between the waste heat boiler 6 and the hot water pump 4, that is, the water inlet of the deaerator 5 is connected to the water outlet of the hot water pump 4, and the water outlet of the deaerator 5 is connected to the water inlet of the waste heat boiler 6. During use, the deaerator 5 is used to remove non-condensable gases such as oxygen and carbon dioxide from hot water, so that, on the one hand, the subsequent equipment and its steam-water system pipelines can be prevented from being corroded, and on the other hand, the heat transfer effect can be improved.

[0043] In some embodiments, the water outlet of the steam turbine 7 is connected to a hot water pipe, and the hot water pipe is used to supply water to the water user. Specifically, the water discharged from the steam turbine 7 has a relatively high temperature, so the water discharged from the steam turbine 7 can be transported to the hot water pipe, and then transported to the water user by the hot water pipe. Compared with the method of using electric energy to heat water, this can reduce energy consumption.

[0044] In some embodiments, the water outlet of the steam turbine 7 is connected to the water inlet of the air-water heat exchanger 1 through the condenser 9. Specifically, the water outlet of the steam turbine 7 is connected to the water inlet of the condenser 9, and the water outlet of the condenser 9 is connected to the water inlet of the air-water heat exchanger 1. During use, the steam discharged after work in the steam turbine 7 can be returned to the air-water heat exchanger 1 through the condenser 9 for recycling. It should be understood that when the steam passes through the condenser 9, it can release heat to condense into water. Specifically, a cooling medium circulation pipeline is provided inside the condenser 9, and the cooling medium flows in the pipeline, taking away the heat of the steam, so that the steam is cooled and condensed into water.

[0045] In some embodiments, a booster pump 10 is provided between the steam turbine 7 and the air-water heat exchanger 1. Specifically, the booster pump 10 is provided between the air-water heat exchanger 1 and the condenser 9, that is, the water inlet of the booster pump 10 is connected to the water outlet of the condenser 9, and the water outlet of the booster pump 10 is connected to the water inlet of the air-water heat exchanger 1. During use, the booster pump 10 can pressurize the condensed water to transport the condensed water to the air-water heat exchanger 1.

[0046] In some embodiments, the system further includes a first tail gas emission unit, the air inlet of the first tail gas emission unit is connected to the air outlet of the air-water heat exchanger 1, and is used to discharge the tail gas of the air-water heat exchanger 1. Specifically, the first tail gas emission unit includes a flue gas purification system 2 and a first flue gas exhaust boiler 3, the air inlet of the flue gas purification system 2 is connected to the air outlet of the air-water heat exchanger 1, and the air inlet of the first flue gas exhaust boiler 3 is connected to the air outlet of the flue gas purification system 2. During use, the tail gas of the air-water heat exchanger 1 can first pass through the flue gas purification system 2, and then be discharged to the atmosphere through the first flue gas exhaust boiler 3. When the tail gas of the air-water heat exchanger 1 passes through the flue gas purification system 2, the dust in the flue gas can be removed by the flue gas purification system 2, so that the flue gas discharged into the atmosphere meets environmental protection requirements.

[0047] In some embodiments, the system further includes a second tail gas emission unit, the air inlet of the second tail gas emission unit is connected to the air outlet of the waste heat boiler 6, and is used to discharge the tail gas of the waste heat boiler 6. Specifically, the second tail gas emission unit includes a dust removal system 11 and a second smoke exhaust boiler 12, the air inlet of the dust removal system 11 is connected to the air outlet of the waste heat boiler 6, and the air inlet of the second smoke exhaust boiler 12 is connected to the air outlet of the dust removal system 11. During use, the tail gas of the waste heat boiler 6 can first pass through the dust removal system 11, and then be discharged to the atmosphere through the second smoke exhaust boiler 12. When the tail gas of the waste heat boiler 6 passes through the dust removal system 11, the dust in the flue gas can be removed by the dust removal system 11, so that the flue gas discharged into the atmosphere meets environmental protection requirements.

[0048] According to the above scheme, the system can recycle the heat in the flue gas of electrolytic aluminum and the flue gas of the thermal electric furnace of the silicon plant to generate electricity. In this way, on the one hand, it can reduce the waste heat loss of the aluminum plant, and on the other hand, it can improve the efficiency of waste heat power generation, thereby achieving the purpose of saving energy.

[0049] The present application also provides a method for utilizing waste heat from two silicon and aluminum plants, which is applicable to the above-mentioned system for utilizing waste heat from two silicon and aluminum plants. The method includes:

[0050] Step S100, the aluminum plant fume output device 13 discharges the aluminum plant electrolytic aluminum fume into the air-water heat exchanger 1, and the air-water heat exchanger 1 recovers the heat in the aluminum plant electrolytic aluminum fume to form hot water;

[0051] Step S200: The silicon plant thermal furnace 14 discharges the generated thermal furnace flue gas into the waste heat boiler 6, and the waste heat boiler 6 recovers the heat in the thermal furnace flue gas to heat hot water to form high-temperature and high-pressure steam;

[0052] Step S300: The steam turbine 7 converts the thermal energy of the high-temperature and high-pressure steam into mechanical energy to drive the generator 8 to generate electricity.

[0053] In step S100, the process of forming hot water by the air-water heat exchanger 1 is as follows: since the aluminum electrolysis plant generates a large amount of aluminum electrolysis flue gas during the production process, the flue gas has a certain amount of heat resources. The aluminum electrolysis plant flue gas output device 13 can discharge the aluminum electrolysis flue gas into the air-water heat exchanger 1, and the aluminum electrolysis flue gas of the aluminum plant exchanges heat with the low-temperature water passing through the air-water heat exchanger 1, so that the low-temperature water forms hot water.

[0054] In step S100, the parameters of the hot water may include: a temperature of 125°C and a pressure of 0.35-0.4 MPa.

[0055] In step S100, the first tail gas discharge unit discharges the tail gas of the air-water heat exchanger 1. Specifically, the tail gas of the air-water heat exchanger 1 first passes through the flue gas purification system 2, and then is discharged to the atmosphere through the first flue gas exhaust boiler 3. When the tail gas of the air-water heat exchanger 1 passes through the flue gas purification system 2, the dust in the flue gas can be removed by the flue gas purification system 2, so that the flue gas discharged to the atmosphere meets environmental protection requirements.

[0056] In step S200, the process of the waste heat boiler 6 forming high-temperature and high-pressure steam is as follows: since the silicon plant thermal electric furnace 14 generates a large amount of thermal electric furnace flue gas during the combustion process, the flue gas has a large amount of heat resources. The silicon plant thermal electric furnace 14 can discharge the thermal electric furnace flue gas generated by the combustion into the waste heat boiler 6, and the thermal electric furnace flue gas is heat-exchanged with the hot water passing through the waste heat boiler 6, so that the hot water forms high-temperature and high-pressure steam.

[0057] In step S200, the parameters of the high-temperature and high-pressure steam may include: a temperature of 450°C and a pressure of 3.82 MPa.

[0058] In step S200, the second tail gas discharge unit discharges the tail gas of the waste heat boiler 6. Specifically, the tail gas of the waste heat boiler 6 can first pass through the dust removal system 11 to remove dust, and then be discharged to the atmosphere through the second smoke exhaust boiler 12. When the tail gas of the waste heat boiler 6 passes through the dust removal system 11, the dust in the flue gas can be removed by the dust removal system 11, so that the flue gas discharged to the atmosphere meets environmental protection requirements.

[0059] In step S300, the process of the steam turbine 7 driving the generator 8 to generate electricity is as follows: the high-temperature and high-pressure steam generated by the waste heat boiler 6 has sufficient energy to do work to drive the steam turbine 7, so that the shaft of the steam turbine 7 rotates. When the shaft of the steam turbine 7 rotates, it will drive the shaft of the generator 8 to rotate, thereby realizing the conversion of thermal energy into electrical energy.

[0060] In step S300, the steam after work can be returned to the gas-water heat exchanger 1 through the condenser 9 for circulation. When the steam passes through the condenser 9, it can release heat to condense into water. Specifically, a cooling medium circulation pipeline is provided inside the condenser 9, and the cooling medium flows in the pipeline to take away the heat of the steam, so that the steam is cooled and condensed into water.

[0061] According to the above scheme, the system can recycle the heat in the flue gas of electrolytic aluminum and the flue gas of the thermal electric furnace of the silicon plant to generate electricity. In this way, on the one hand, it can reduce the waste heat loss of the aluminum plant, and on the other hand, it can improve the efficiency of waste heat power generation, thereby achieving the purpose of saving energy.

[0062] One or more embodiments of this specification are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this specification should be included in the scope of protection of this application.

[0063] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A system combining waste heat utilization of silicon and aluminum plants, characterized in that: include: Aluminum plant flue gas output device, air-water heat exchanger, first tail gas emission unit, silicon plant thermal electric furnace, waste heat boiler, second tail gas emission unit, steam turbine and generator; The aluminum plant fume output device is used to discharge the aluminum electrolytic aluminum fume of the aluminum plant; The air inlet of the air-water heat exchanger is connected to the air outlet of the aluminum plant fume output device, and is used to recover the heat in the aluminum electrolysis fume of the aluminum plant to form hot water; The air inlet of the first tail gas discharge unit is connected to the air outlet of the air-water heat exchanger, and is used to discharge the tail gas of the air-water heat exchanger; The silicon plant thermal furnace is used to burn and generate thermal furnace flue gas; The water inlet of the waste heat boiler is connected to the water outlet of the gas-water heat exchanger, and the air inlet of the waste heat boiler is connected to the air outlet of the thermal electric furnace of the silicon plant, so as to recover the heat in the flue gas of the thermal electric furnace to form high-temperature and high-pressure steam; The air inlet of the second tail gas discharge unit is connected to the air outlet of the waste heat boiler, and is used to discharge the tail gas of the waste heat boiler; The steam inlet of the steam turbine is connected to the steam outlet of the waste heat boiler, and is used to convert the thermal energy of the high-temperature and high-pressure steam into mechanical energy to drive the generator to generate electricity.

2. The system for utilizing waste heat from silicon and aluminum plants according to claim 1 is characterized in that: The temperature of the hot water is 125° C. and the pressure is 0.35-0.4 MPa.

3. The system for utilizing waste heat from silicon and aluminum plants according to claim 1 is characterized in that: The temperature of the high-temperature and high-pressure steam is 450° C. and the pressure is 3.82 MPa.

4. The system for utilizing waste heat from silicon and aluminum plants according to claim 1 is characterized in that: A hot water pump is arranged between the gas-water heat exchanger and the waste heat boiler.

5. The system for utilizing waste heat from silicon and aluminum plants according to claim 1 is characterized in that: A deaerator is arranged between the waste heat boiler and the gas-water heat exchanger.

6. The system for utilizing waste heat from silicon and aluminum plants according to claim 1 is characterized in that: The water outlet of the steam turbine is connected to a hot water pipe, and the hot water pipe is used to supply water to the water-using end.

7. The system for utilizing waste heat from silicon and aluminum plants according to claim 1 is characterized in that: The water outlet of the steam turbine is connected to the water inlet of the air-water heat exchanger through a condenser.

8. The system for utilizing waste heat from silicon and aluminum plants according to claim 7 is characterized in that: A booster pump is arranged between the steam turbine and the gas-water heat exchanger.

9. The system for utilizing waste heat from silicon and aluminum plants according to claim 1 is characterized in that: The first tail gas emission unit and the second tail gas emission unit both include a flue gas purification device.

10. A method for utilizing waste heat from two silicon and aluminum plants, applicable to the system for utilizing waste heat from two silicon and aluminum plants as claimed in any one of claims 1 to 9, characterized in that: include: The aluminum plant fume output device discharges the aluminum plant electrolytic aluminum fume into the air-water heat exchanger, and the air-water heat exchanger recovers the heat in the aluminum plant electrolytic aluminum fume to form hot water; The silicon plant thermal furnace discharges the generated thermal furnace flue gas into the waste heat boiler, and the waste heat boiler recovers the heat in the thermal furnace flue gas to heat the hot water to form high-temperature and high-pressure steam; The steam turbine converts the thermal energy of high-temperature and high-pressure steam into mechanical energy to drive the generator to generate electricity.

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