Waste heat power generation system of steelmaking sintering circular cooler

Abstract

The utility model discloses a steelmaking sintering circular cooler waste heat power generation system which comprises a circular cooler, a steam turbine, a power generator, a first-stage economizer, a second-stage economizer, an evaporator, a steam pocket, a first-stage superheater, a second-stage superheater, a phase change energy storage system and a control system. The phase change energy storage system comprises a heat storage tank, a heat release storage tank, a first temperature sensor, a second temperature sensor, a flue gas three-way valve and a steam three-way valve; the first temperature sensor is arranged on the heat storage tank, the second temperature sensor is arranged on the heat release tank, and the flue gas three-way valve, the steam three-way valve, the first temperature sensor and the second temperature sensor are electrically connected to the control system, so that redundant heat can be stored in the heat storage tank and the heat release tank when waste heat is sufficient; heat waste is avoided, the stored heat is released when the waste heat is insufficient, sufficient and flexible utilization of the waste heat of the circular cooler is achieved, and the waste heat recovery efficiency is improved.

Description

Technical Field

[0001] This utility model relates to the field of waste heat power generation systems, and in particular to a waste heat power generation system for a steelmaking sintering ring cooler. Background Technology

[0002] In the steel production process, the sintering process generates a large amount of high-temperature flue gas. The waste heat carried by this flue gas has high recovery value. The waste heat of the high-temperature flue gas generated during steelmaking is a high-grade thermal energy resource. At present, waste heat boilers are widely used to recover and utilize high-temperature flue gas.

[0003] Traditional waste heat power generation systems for steelmaking sintering annular coolers typically include an annular cooler, a steam turbine, a generator, and multi-stage heat exchange equipment (such as economizers, evaporators, and superheaters). Specifically, the high-temperature, medium-temperature, and low-temperature flue gas ends of the annular cooler are connected to different heat exchange devices, and steam is generated through heat exchange to drive the steam turbine to generate electricity.

[0004] In recent years, phase change materials (PCMs) have emerged as a thermal energy storage technology. For example, a waste heat recovery system based on molten salt thermal energy storage uses a single-tank design. When the sintering machine generates high-temperature flue gas (heat storage demand), it often coincides with the off-peak period of power generation load (low heat release demand). However, during peak power generation (high steam demand), there is insufficient waste heat from the flue gas. The single-tank design cannot achieve simultaneous heat storage and heat release. As a result, during the heat storage stage, the temperature of the molten salt in the tank rises to over 250°C, but the excess heat cannot be utilized immediately and can only be vented through the chimney (energy waste rate as high as 35%). During the heat release stage, after the heat in the tank is quickly depleted, the supplementary combustion system is forced to be activated (fuel costs increase by 40%).

[0005] Therefore, a new technical solution needs to be researched to address the above problems. Utility Model Content

[0006] In view of this, the present invention addresses the deficiencies of existing technologies and its main objective is to provide a waste heat power generation system for steelmaking sintering ring coolers. Through the design of a phase change energy storage system, excess heat can be stored in heat storage tanks and heat release tanks when waste heat is sufficient, avoiding heat waste. When waste heat is insufficient, the stored heat is released, achieving full and flexible utilization of the ring cooler's waste heat, improving waste heat recovery efficiency. Furthermore, its connection to the steam drum allows for timely replenishment of heat according to steam demand, stabilizing the pressure and temperature of the steam within the steam drum. This ensures stable steam parameters at the turbine inlet, guaranteeing stable operation of the power generation system, reducing the problem of decreased power generation efficiency due to steam parameter fluctuations, and improving the reliability of the power generation system.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A waste heat power generation system for a steelmaking sintering ring cooler includes a ring cooler, a steam turbine, a generator, a primary economizer, a secondary economizer, an evaporator, a steam drum, a primary superheater, and a secondary superheater. The ring cooler has a low-temperature flue gas end, a medium-temperature flue gas end, and a high-temperature flue gas end. The output end of the steam turbine is connected to the input end of the generator. The low-temperature flue gas end is connected to the secondary economizer. The output end of the medium-temperature flue gas end is connected to the input end of the evaporator. The output end of the evaporator is connected to the primary economizer. The output end of the primary economizer is connected to the other output end of the secondary economizer.

[0009] The waste heat power generation system of the steelmaking sintering ring cooler also includes a phase change energy storage system and a control system.

[0010] The phase change energy storage system includes a heat storage tank, a heat release tank, a first temperature sensor, a second temperature sensor, a flue gas three-way valve, and a steam three-way valve.

[0011] The flue gas three-way valve is used to control the flue gas flow direction at the outlet of the secondary economizer, and the steam three-way valve is used to control the heating path of the heat release tank; both the heat storage tank and the heat release tank are equipped with a flue gas heat exchanger end and a steam outlet.

[0012] The flue gas three-way valve has a first flue gas inlet, a first flue gas outlet, and a second flue gas outlet. The first flue gas inlet is connected to the other output end of the secondary economizer. The first flue gas outlet is connected to the flue gas heat exchanger end of the heat storage tank, and the second flue gas outlet is connected to the flue gas heat exchanger end of the heat release tank. The steam three-way valve has a first steam inlet, a second steam inlet, and a steam outlet. The first steam inlet is connected to the steam outlet of the heat storage tank, the second steam inlet is connected to the steam outlet of the heat release tank, and the steam outlet is connected to the inlet of the steam drum.

[0013] The first temperature sensor is installed on the heat storage tank, and the second temperature sensor is installed on the heat release tank. The flue gas three-way valve, the steam three-way valve, the first temperature sensor, and the second temperature sensor are electrically connected to the control system.

[0014] As a preferred option, when the temperature of the heat storage tank is lower than the set value, the control system controls the flue gas three-way valve to guide the flue gas from the secondary economizer to the heat storage tank; when the temperature of the heat release tank is higher than the set value, the control system controls the steam three-way valve to output steam to the steam drum.

[0015] As a preferred embodiment, a high-temperature resistant dust collector is also installed between the annular cooler and the low-temperature flue gas end, the medium-temperature flue gas end, and the high-temperature flue gas end. The high-temperature resistant dust collector is equipped with a low-temperature purification output end, a medium-temperature purification output end, and a high-temperature purification output end. The low-temperature purification output end is connected to the input end of the low-temperature flue gas end; the medium-temperature purification output end is connected to the input end of the medium-temperature flue gas end; and the high-temperature purification output end is connected to the input end of the high-temperature flue gas end. This reduces dust wear on parts, improves combustion efficiency, and reduces fuel consumption.

[0016] As a preferred embodiment, the flue gas three-way valve is an electric flue gas three-way valve; the steam three-way valve is an electric steam three-way valve.

[0017] As a preferred embodiment, the heat storage tank is equipped with high-temperature molten salt.

[0018] As a preferred embodiment, the heat release tank is equipped with medium-temperature molten salt.

[0019] Compared with the prior art, this utility model has obvious advantages and beneficial effects. Specifically, as can be seen from the above technical solution, it mainly achieves this through the design of a phase change energy storage system. The phase change energy storage system includes a heat storage tank, a heat release tank, a first temperature sensor, a second temperature sensor, a flue gas three-way valve, and a steam three-way valve. In this way, when there is sufficient waste heat, excess heat can be stored in the heat storage tank and the heat release tank to avoid heat waste. When there is insufficient waste heat, the stored heat can be released, realizing the full and flexible utilization of the waste heat of the annular cooler and improving the waste heat recovery efficiency.

[0020] Secondly, the phase change energy storage system is connected to the steam drum, which can replenish heat in a timely manner according to the steam demand and stabilize the pressure and temperature of the steam in the steam drum. This makes the steam parameters at the turbine inlet stable, ensuring the stable operation of the power generation system, reducing the problem of power generation efficiency decline caused by steam parameter fluctuations, and improving the reliability of the power generation system.

[0021] Next, the control system connects the first temperature sensor, the second temperature sensor, the flue gas three-way valve, and the steam three-way valve via electrical connection. It can monitor the temperature of the heat storage tank and the heat release tank in real time, and accurately control the flue gas flow direction and heating path according to temperature changes. It can better adapt to the fluctuations generated by waste heat, optimize system operation, and further improve energy utilization efficiency.

[0022] Finally, the connection method of components such as the evaporator, primary economizer, and secondary economizer enables cascaded utilization of heat and enhances the collaborative working ability between components. Combined with the phase change energy storage system, it achieves efficient conversion of waste heat and stable steam production, thus improving the overall reliability of the power generation system.

[0023] To more clearly illustrate the structural features and effects of this utility model, the following detailed description of this utility model is provided in conjunction with the accompanying drawings and specific embodiments. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the first control flow according to an embodiment of the present utility model;

[0025] Figure 2 This is a schematic diagram of the second control flow according to an embodiment of the present utility model;

[0026] Figure 3 This is a schematic diagram of the third control flow according to an embodiment of the present invention.

[0027] Explanation of reference numerals in the attached diagram:

[0028] 1. Circular cooler 2. Steam turbine

[0029] 111. Low-temperature flue gas end; 112. Medium-temperature flue gas end

[0030] 113. High-temperature flue gas end

[0031] 3. Generator; 4. Primary economizer

[0032] 5. Secondary economizer 6. Steam drum

[0033] 7. Primary superheater; 8. Secondary superheater

[0034] 9. Phase change energy storage system 10. Control system

[0035] 11. High-temperature dust collector 12. Flash evaporator

[0036] 13. Evaporator

[0037] 91. Thermal storage tank; 92. Thermal release storage tank

[0038] 93. First temperature sensor 94. Second temperature sensor

[0039] 95. Flue gas three-way valve 96. Steam three-way valve

[0040] 951. First flue gas inlet; 952. First flue gas outlet

[0041] 953. Second flue gas outlet

[0042] 961. First steam inlet; 962. Second steam inlet

[0043] 963. Steam outlet

[0044] 97. Flue gas heat exchanger end; 98. Steam outlet. Detailed Implementation

[0045] Please refer to Figures 1 to 3 As shown, it illustrates the specific structure of an embodiment of the present invention.

[0046] In the description of this utility model, it should be noted that the directional terms such as "up", "down", "front", "back", "left", and "right" indicate the orientation and positional relationship based on the accompanying drawings or the orientation or positional relationship shown when wearing and using the device normally. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific protection scope of this utility model.

[0047] A waste heat power generation system for a steelmaking sintering ring cooler 1 includes a ring cooler 1, a steam turbine 2, a generator 3, a primary economizer 4, a secondary economizer 5, an evaporator 13, a steam drum 6, a primary superheater 7, and a secondary superheater 8.

[0048] The annular cooler 1 has a low-temperature flue gas end 111, a medium-temperature flue gas end 112, and a high-temperature flue gas end 113; the output end of the steam turbine 2 is connected to the input end of the generator 3; the low-temperature flue gas end 111 is connected to the secondary economizer 5; the output end of the medium-temperature flue gas end 112 is connected to the input end of the evaporator 13; the output end of the evaporator 13 is connected to the primary economizer 4; and the output end of the primary economizer 4 is connected to the other output end of the secondary economizer 5.

[0049] The waste heat power generation system of the steelmaking sintering ring cooler 1 also includes a phase change energy storage system 9 and a control system 10; the phase change energy storage system 9 includes a heat storage tank 91, a heat release tank 92, a first temperature sensor 93, a second temperature sensor 94, a flue gas three-way valve 95, and a steam three-way valve 96.

[0050] The flue gas three-way valve 95 is used to control the flue gas flow direction at the outlet of the secondary economizer 5, and the steam three-way valve 96 is used to control the heating path of the heat release tank 92; both the heat storage tank 91 and the heat release tank 92 are equipped with a flue gas heat exchanger end 97 and a steam outlet 98.

[0051] The flue gas three-way valve 95 has a first flue gas inlet 951, a first flue gas outlet 952, and a second flue gas outlet 953. The first flue gas inlet 951 is connected to the other output end of the secondary economizer 5. The first flue gas outlet 952 is connected to the flue gas heat exchanger end 97 of the heat storage tank 91, and the second flue gas outlet 953 is connected to the flue gas heat exchanger end 97 of the heat release tank 92. The steam three-way valve 96 has a first steam inlet 961, a second steam inlet 962, and a steam outlet 963. The first steam inlet 961 is connected to the steam outlet 98 of the heat storage tank 91, and the second steam inlet 962 is connected to the steam outlet 98 of the heat release tank 92. The steam outlet 963 is connected to the inlet of the steam drum 6.

[0052] The first temperature sensor 93 is mounted on the heat storage tank 91, and the second temperature sensor 94 is mounted on the heat release tank 92. The flue gas three-way valve 95, the steam three-way valve 96, the first temperature sensor 93, and the second temperature sensor 94 are electrically connected to the control system 10. The electric three-way valve has a temperature ≥300℃. Preferably, the flue gas three-way valve 95 is an electric flue gas three-way valve, and the steam three-way valve 96 is an electric steam three-way valve.

[0053] Preferably, when the temperature of the heat storage tank 91 is lower than the set value, the control system 10 controls the flue gas three-way valve 95 to guide the flue gas from the secondary economizer 5 to the heat storage tank 91; when the temperature of the heat release tank 92 is higher than the set value, the control system 10 controls the steam three-way valve 96 to output steam to the steam drum 6; when the first temperature sensor 93 detects that the temperature of the heat storage tank 91 is lower than 200°C, the control system controls the flue gas three-way valve 95 to guide the flue gas to the heat storage tank 91; when the second temperature sensor 94 detects that the temperature of the heat release tank 92 is higher than 220°C, the control system controls the steam three-way valve 96 to output steam to the steam drum 6, so that the control system 10 switches the heat storage / heat release mode according to the temperature sensor data.

[0054] In this embodiment, the alternating operation of the dual tanks in the phase change energy storage system 9 can be divided into multiple stages. The system 10 automatically switches between these stages by real-time monitoring and control using corresponding temperature sensors, thereby achieving efficient recovery and stable release of waste heat.

[0055] Initial phase (system startup)

[0056] The thermal storage tank 91 (filled with high-temperature molten salt, phase change temperature 220℃) is in standby mode, and the temperature is maintained at 200℃.

[0057] The heat release storage tank 92 (filled with medium-temperature molten salt, phase change temperature 142℃) maintains an operating temperature of 240℃;

[0058] The flue gas three-way valve 95 by default directs the flue gas (approximately 225°C) from the outlet of the secondary economizer 5 to the heat storage tank 91, and the steam three-way valve 96 connects the heat release tank 92 to the heat storage-heat release stage of the steam drum 6 (normal operation).

[0059] When the first temperature sensor 93 detects that the temperature of the thermal storage tank 91 is <210℃:

[0060] 1. The flue gas three-way valve 95 keeps the first output port open, and the flue gas heats the molten salt to 250°C through the heat exchanger of the heat storage tank 91;

[0061] 2. The cooled flue gas (approximately 180°C) returns to the main flue.

[0062] 3. Molten salt in heat release tank 92 generates 1.5MPa saturated steam through a steam heat exchanger to maintain stable pressure in steam drum 6;

[0063] 4. The control system 10 compares the temperature difference between the two tanks in real time to prevent heat backflow during the transition phase (when heat storage is complete);

[0064] When the temperature of heat storage tank 91 is ≥250℃ and the temperature of heat release tank 92 is ≤190℃:

[0065] 1. The flue gas three-way valve 95 switches to the second output port within 5 seconds, and the flue gas is diverted to enter the heat release storage tank 92;

[0066] 2. The steam three-way valve 96 switches synchronously to connect the heat storage tank 91 to the steam drum 6 system;

[0067] 3. The original heat release storage tank 92 was switched to heat storage mode and began to store waste heat from the flue gas;

[0068] 4. The afterburning system fine-tunes the fuel quantity based on the pressure of steam drum 6 (fluctuation <5%).

[0069] Preferably, a high-temperature resistant dust collector 11 is further provided between the annular cooler 1 and the low-temperature flue gas end 111, the medium-temperature flue gas end 112, and the high-temperature flue gas end 113. The high-temperature resistant dust collector 11 is provided with a low-temperature purification output end, a medium-temperature purification output end, and a high-temperature purification output end. The low-temperature purification output end is connected to the input end of the low-temperature flue gas end 111; the medium-temperature purification output end is connected to the input end of the medium-temperature flue gas end 112; and the high-temperature purification output end is connected to the input end of the high-temperature flue gas end 113. This reduces the wear of parts by dust, while improving combustion efficiency and reducing fuel consumption.

[0070] Preferably, the heat storage tank 91 is filled with high-temperature molten salt (NaNO3-KNO3) with a temperature range of 220-400℃, which is used in the main heat storage unit to receive waste heat from the secondary economizer 5. Preferably, the heat release tank 92 is filled with medium-temperature molten salt (low-melting-point mixed molten salt) at 150-300℃, which is used for rapid heat release and prioritizes supplying the needs of the steam drum 6. Both tanks are filled with molten salt. The heat storage tank 91 uses high-temperature molten salt to maximize heat storage capacity, while the heat release tank 92 uses medium- and low-temperature molten salt to improve operational safety, thus achieving an optimal balance between energy efficiency, reliability, and cost. Taking molten salt PCM as an example: In the heat release stage, liquid molten salt (250℃) flows in the shell side of the heat exchanger, heating the water in the tube side. After absorbing heat, the water becomes saturated steam (1.5MPa) and is transported to the steam drum 6 or the secondary superheater 8. After the molten salt temperature drops to 200℃, it returns to the storage tank to wait for heat storage again. In the energy storage stage (heating PCM through flue gas), the flue gas heats the molten salt to a liquid state (e.g., 250℃) through the flue gas-PCM heat exchanger to store heat.

[0071] In this embodiment, a flash evaporator 12 is also provided. The flash steam from the outlet of the flash evaporator 12 is connected to the turbine 2 to drive the generator 3 to generate electricity. The water from the outlet below the flash evaporator 12, together with the exhaust steam from the turbine 2 and the water entering the condensate pump through the condenser, enters the feedwater pump to supply the economizer for circulation.

[0072] The key design feature of this utility model lies in its phase change energy storage system, which includes a heat storage tank, a heat release tank, a first temperature sensor, a second temperature sensor, a flue gas three-way valve, and a steam three-way valve. This allows excess heat to be stored in the heat storage tank and the heat release tank when there is sufficient waste heat, preventing heat waste, and releasing the stored heat when there is insufficient waste heat. This achieves full and flexible utilization of the waste heat from the annular cooler, improving waste heat recovery efficiency.

[0073] Secondly, the phase change energy storage system is connected to the steam drum, which can replenish heat in a timely manner according to the steam demand and stabilize the pressure and temperature of the steam in the steam drum. This makes the steam parameters at the turbine inlet stable, ensuring the stable operation of the power generation system, reducing the problem of power generation efficiency decline caused by steam parameter fluctuations, and improving the reliability of the power generation system.

[0074] Next, the control system connects the first temperature sensor, the second temperature sensor, the flue gas three-way valve, and the steam three-way valve via electrical connection. It can monitor the temperature of the heat storage tank and the heat release tank in real time, and accurately control the flue gas flow direction and heating path according to temperature changes. It can better adapt to the fluctuations generated by waste heat, optimize system operation, and further improve energy utilization efficiency.

[0075] Finally, the connection method of components such as the evaporator, primary economizer, and secondary economizer enables cascaded utilization of heat and enhances the collaborative working ability between components. Combined with the phase change energy storage system, it achieves efficient conversion of waste heat and stable steam production, thus improving the overall reliability of the power generation system.

[0076] The above description is merely a preferred embodiment of the present utility model and does not constitute any limitation on the technical scope of the present utility model. Therefore, any minor modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present utility model shall still fall within the scope of the technical solution of the present utility model.

Claims

1. A waste heat power generation system for a steelmaking sintering ring cooler, comprising a ring cooler, a steam turbine, a generator, a primary economizer, a secondary economizer, an evaporator, a steam drum, a primary superheater, and a secondary superheater; the ring cooler has a low-temperature flue gas end, a medium-temperature flue gas end, and a high-temperature flue gas end; the output end of the steam turbine is connected to the input end of the generator; the low-temperature flue gas end is connected to the secondary economizer; the output end of the medium-temperature flue gas end is connected to the input end of the evaporator; the output end of the evaporator is connected to the primary economizer; and the output end of the primary economizer is connected to another output end of the secondary economizer. Its features are: The waste heat power generation system of the steelmaking sintering ring cooler also includes a phase change energy storage system and a control system. The phase change energy storage system includes a heat storage tank, a heat release tank, a first temperature sensor, a second temperature sensor, a flue gas three-way valve, and a steam three-way valve. The flue gas three-way valve is used to control the flue gas flow direction at the outlet of the secondary economizer, and the steam three-way valve is used to control the heating path of the heat release tank; both the heat storage tank and the heat release tank are equipped with a flue gas heat exchanger end and a steam outlet. The flue gas three-way valve has a first flue gas inlet, a first flue gas outlet, and a second flue gas outlet. The first flue gas inlet is connected to the other output end of the secondary economizer. The first flue gas outlet is connected to the flue gas heat exchanger end of the heat storage tank, and the second flue gas outlet is connected to the flue gas heat exchanger end of the heat release tank. The steam three-way valve has a first steam inlet, a second steam inlet, and a steam outlet. The first steam inlet is connected to the steam outlet of the heat storage tank, the second steam inlet is connected to the steam outlet of the heat release tank, and the steam outlet is connected to the inlet of the steam drum. The first temperature sensor is installed on the heat storage tank, and the second temperature sensor is installed on the heat release tank. The flue gas three-way valve, the steam three-way valve, the first temperature sensor, and the second temperature sensor are electrically connected to the control system.

2. The waste heat power generation system for steelmaking sintering ring cooler according to claim 1, characterized in that: When the temperature of the heat storage tank is lower than the set value, the control system controls the flue gas three-way valve to guide the flue gas from the secondary economizer to the heat storage tank; when the temperature of the heat release tank is higher than the set value, the control system controls the steam three-way valve to output steam to the steam drum.

3. The waste heat power generation system for steelmaking sintering ring cooler according to claim 1, characterized in that: A high-temperature resistant dust collector is also installed between the annular cooler and the low-temperature flue gas end, the medium-temperature flue gas end, and the high-temperature flue gas end. The high-temperature resistant dust collector is equipped with a low-temperature purification output end, a medium-temperature purification output end, and a high-temperature purification output end. The low-temperature purification output end is connected to the input end of the low-temperature flue gas end; the medium-temperature purification output end is connected to the input end of the medium-temperature flue gas end; and the high-temperature purification output end is connected to the input end of the high-temperature flue gas end.

4. The waste heat power generation system for steelmaking sintering ring cooler according to claim 1, characterized in that: The flue gas three-way valve is an electric flue gas three-way valve; the steam three-way valve is an electric steam three-way valve.

5. The waste heat power generation system for steelmaking sintering ring cooler according to claim 1, characterized in that: The heat storage tank is equipped with high-temperature molten salt.

6. The waste heat power generation system for steelmaking sintering ring cooler according to claim 1, characterized in that: The heat release storage tank is equipped with medium-temperature molten salt.

Images