Pellet sintering low-temperature waste heat combined recovery driving and power generation system

Abstract

The application relates to the technical field of waste heat recovery, in particular to a pellet sintering low-temperature waste heat combined recovery drag and power generation system, which comprises the following: a flue gas mixer used for mixing sintering ring cooling low-temperature flue gas and pellet rotary kiln high-temperature flue gas; a flue gas waste heat boiler connected with the flue gas mixer and used for converting the temperature of the mixed sintering ring cooling low-temperature flue gas and the pellet rotary kiln high-temperature flue gas into low-temperature flue gas and generating superheated low-pressure steam; a high-speed steam turbine connected with the flue gas waste heat boiler and used for doing work under the drive of the superheated low-pressure steam; the high-speed steam turbine has the functions of drag and power generation; and a motor generator connected with the high-speed steam turbine, wherein the motor generator has the functions of drag and power generation. The pellet sintering low-temperature waste heat combined recovery drag and power generation system provided by the application is convenient for saving energy and improving the utilization rate of flue gas waste heat.

Description

Technical Field

[0001] This application relates to the field of waste heat recovery technology, specifically to a combined low-temperature waste heat recovery and power generation system for pellet sintering. Background Technology

[0002] my country is a major steel producer, with blast furnace ironmaking consuming a significant amount of energy. In particular, the sintering and pelletizing processes account for 27% of total energy consumption for steel enterprises. To reduce energy consumption, steel companies are focusing on utilizing waste heat resources in their production processes. Currently, waste heat recovery technology has been successfully applied in pelletizing and sintering production systems, achieving significant economic benefits. Waste heat resources in pelletizing and sintering processes account for approximately 45% of the waste heat generated in blast furnace ironmaking. Improving the utilization efficiency of waste heat recovery systems can not only reduce energy consumption indicators but also save substantial amounts of energy for society and enterprises, while reducing thermal pollution during production.

[0003] The waste heat recovery process for pelletizing rotary kilns involves recovering and utilizing the waste heat from the kiln, with the heated air being used to generate steam in a waste heat boiler. However, the high temperature and low flow rate of the pelletizing waste heat flue gas result in low steam output from the waste heat boiler. In most cases, the steam produced is used as a heating medium, leading to a low waste heat recovery utilization rate and low efficiency.

[0004] The waste heat recovery process for sintering annular coolers involves recovering and utilizing the waste heat from the annular cooler. This waste heat is exchanged with a waste heat boiler to generate steam at a specific temperature and pressure. Currently, waste heat recovery only targets the high-temperature section of the annular cooler, while the low-temperature section is either discharged into the air or recirculated as hot air. This portion of the flue gas, with its low temperature and high flow rate, is not effectively recovered, leading to a waste of sintering waste heat resources.

[0005] In existing pelletizing and sintering waste heat recovery systems, the main power-consuming and core equipment is the induced draft fan, which accounts for approximately 23% of the total power consumption of waste heat recovery. The power consumption of the induced draft fan affects the efficiency of waste heat recovery to a certain extent and also reduces the economic value of waste heat recovery. Utility Model Content

[0006] To improve the utilization rate of flue gas waste heat, this application provides a combined low-temperature waste heat recovery system for pellet sintering, driving, and power generation.

[0007] The technical solution provided in this application for a combined low-temperature waste heat recovery and power generation system for pellet sintering is as follows:

[0008] A combined low-temperature waste heat recovery system for pellet sintering, used for traction and power generation, comprising:

[0009] A flue gas mixer is used to mix low-temperature flue gas from the sintering ring with high-temperature flue gas from the pelletizing rotary kiln.

[0010] A flue gas waste heat boiler, connected to the flue gas mixer, is used to convert the temperature of the mixed sintering ring cold low-temperature flue gas and pellet rotary kiln high-temperature flue gas into low-temperature flue gas and generate superheated low-pressure steam.

[0011] A high-speed steam turbine is connected to the flue gas waste heat boiler and is used to perform work driven by superheated low-pressure steam; the high-speed steam turbine has both traction and power generation functions.

[0012] An electric generator is connected to the high-speed steam turbine, and the electric generator has both driving and power generation functions.

[0013] In one specific implementation, a speed-changing clutch is provided between the high-speed steam turbine and the electric motor, the speed-changing clutch being used to change the connection state between the high-speed steam turbine and the electric generator.

[0014] In one specific implementation scheme, a high-voltage automatic grid-connected power distribution device is also included, which is connected to the electric generator and is used to receive electrical energy generated by the electric generator or to supply power to the electric generator.

[0015] In one specific implementation scheme, a circulating cooling device is also included, one end of which is connected to the high-speed steam turbine and the other end of which is connected to the flue gas waste heat boiler.

[0016] In one specific implementation scheme, an induced draft fan is also included, connected to the flue gas waste heat boiler, for discharging low-temperature flue gas.

[0017] In one specific implementation, the induced draft fan is connected to the electric generator, which drives the induced draft fan to discharge low-temperature flue gas.

[0018] In summary, this application includes at least one of the following beneficial technical effects:

[0019] 1. The waste heat recovery and power generation system rationally utilizes the characteristics of the low-temperature exhaust gas from the sintering process's annular cooler, specifically employing the calorific value of the high-temperature exhaust gas from the pelletizing rotary kiln. By increasing the temperature and flow rate of the exhaust gas, the waste heat recovery conversion rate is improved. High-speed turbine output is used for power generation, directly applied to the induced draft fan of the waste heat recovery process system, minimizing energy conversion losses in the induced draft fan. The system uses an electric generator, with a high-voltage automatic grid-connected power distribution device, which effectively reduces electrical system configuration costs, enhances electrical system stability, and increases economic value. A variable-speed clutch enables synchronous operation of the driven units, seamless switching, reduces the impact of equipment operation on the power grid, and ensures system safety.

[0020] 2. After heat exchange in the flue gas waste heat boiler, the mixed flue gas forms low-temperature flue gas, which is then discharged by the induced draft fan. The softened water in the flue gas waste heat boiler forms superheated low-pressure steam after heat exchange. The superheated low-pressure steam drives a high-speed steam turbine to do work. The high-speed steam turbine drives an electric generator through a speed-changing clutch. The electric generator drives the induced draft fan to rotate, so that the thermal energy of the mixed flue gas is converted into the mechanical energy required for the operation of the induced draft fan. At the same time, the electric generator can also convert the excess mechanical energy into electrical energy and recover it to the high-voltage automatic grid-connected power distribution device, which facilitates energy saving and improves the utilization rate of flue gas waste heat. Attached Figure Description

[0021] The accompanying drawings are provided to further understand this application and form part of the specification. They are used together with the embodiments of this application to explain this application and do not constitute a limitation thereof.

[0022] Figure 1 This is a schematic diagram of the overall structure of a pellet sintering low-temperature waste heat recovery combined drive and power generation system according to an embodiment of this application.

[0023] Figure descriptions: 1. Flue gas mixer; 2. Flue gas waste heat boiler; 3. High-speed steam turbine; 4. Electric generator; 5. Speed ​​change clutch; 6. High-voltage automatic grid-connected power distribution device; 7. Circulating cooling device; 8. Exhaust fan. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of this application, unless otherwise stated, "multiple" means two or more.

[0026] The following is in conjunction with the appendix Figure 1 This application will be described in further detail.

[0027] This application discloses a combined low-temperature waste heat recovery and power generation system for pellet sintering.

[0028] Reference Figure 1A combined low-temperature waste heat recovery and power generation system for pellet sintering includes a flue gas mixer 1, a flue gas waste heat boiler 2, a high-speed steam turbine 3, an electric generator 4, a speed-changing clutch 5, a high-voltage automatic grid-connected power distribution device 6, a circulating cooling device 7, and an induced draft fan 8. The flue gas mixer 1 is connected to the flue gas waste heat boiler 2, which has a flue gas pipeline and a softened water pipeline. The induced draft fan 8 is located at the outlet end of the flue gas pipeline of the flue gas waste heat boiler 2. The high-speed steam turbine 3 has an input end, an exhaust end, and a power output end. A steam pipeline and a boiler feedwater pipeline are provided between the high-speed steam turbine 3 and the flue gas waste heat boiler 2. One end of the steam pipeline is connected to the outlet end of the softened water pipeline of the flue gas waste heat boiler 2, and the other end is connected to the input end of the high-speed steam turbine 3. One end of the boiler feedwater pipeline is connected to the exhaust end of the high-speed steam turbine 3, and the other end is connected to the boiler softened water pipeline. At the inlet of the pipeline, the circulating cooling device 7 is located in the middle section of the boiler feedwater pipeline. The power output end of the high-speed steam turbine 3 is connected to the electric generator 4 via a speed-changing clutch 5. The speed-changing clutch 5 can change the connection state between the high-speed steam turbine 3 and the electric generator 4, enabling online, disturbance-free automatic engagement and disengagement. The electric generator 4 is a synchronous electric motor. The input shaft of the electric generator 4 is connected to the low-speed shaft of the speed-changing clutch 5 via a coupling, and the power output end of the high-speed steam turbine 3 is connected to the high-speed shaft of the speed-changing clutch 5 via a coupling. Both the high-speed steam turbine 3 and the electric generator 4 have drive and power generation functions. The output shaft of the electric generator 4 is connected to the induced draft fan 8. When the output shaft of the electric generator 4 rotates, it drives the induced draft fan 8 to rotate, thereby discharging the low-temperature flue gas generated by the flue gas waste heat boiler 2. At the same time, both the electric generator 4 and the high-speed steam turbine 3 can rotate autonomously to perform work under electrical energy drive, and can also generate electrical energy under mechanical energy drive. The power output terminal of the electric generator 4 is electrically connected to the high-voltage automatic grid-connected power distribution device 6. When the electric generator 4 is in generating mode, the generated electrical energy can be input to the high-voltage automatic grid-connected power distribution device 6. When the electric generator 4 is in driving mode, the high-voltage automatic grid-connected power distribution device 6 supplies power to the electric generator 4, driving the electric generator 4 to rotate. The electric generator 4 can drive the induced draft fan 8 to rotate in both driving mode and generating mode.

[0029] The working principle of the evaporator with easy heat exchange tube replacement described in this application is as follows: After the low-temperature flue gas from the sintering ring and the high-temperature flue gas from the pellet rotary kiln enter the flue gas mixer 1, they are fully mixed in the flue gas pipeline. After heat exchange through the softened water pipeline in the flue gas mixer 1, the temperature of the mixed flue gas decreases, forming low-temperature flue gas. The softened water is heated to form superheated low-pressure steam, which is discharged through the outlet of the softened water pipeline and enters the high-speed steam turbine 3 through the steam pipeline. The superheated low-pressure steam drives the high-speed steam turbine 3 to do work. The high-speed steam turbine 3 drives the electric generator 4 to do work through the speed change clutch 5. The output shaft of the electric generator 4 drives the induced draft fan 8 to rotate. The induced draft fan 8 guides the low-temperature flue gas in the flue gas mixer 1 to be discharged. At the same time, the high-speed steam turbine 3 converts the excess mechanical energy into electrical energy through the electric generator 4. The electrical energy is recovered to the power grid by the high-voltage grid-connected power distribution device. In addition, after the superheated low-pressure steam does work through the high-speed steam turbine 3, it forms exhaust steam. The exhaust steam is then cooled by the circulating cooling device 7 to form softened water, which enters the flue gas waste heat boiler 2 through the boiler feedwater pipeline for heat exchange.

[0030] When the high-speed steam turbine 3 is operating at reduced load, or when the operating conditions of the high-speed steam turbine 3 change and the mechanical system is unable to meet the drive power requirements of the entire system, the speed change clutch 5 automatically disengages internally based on the speed, so that the high-speed steam turbine 3 is no longer connected to the electric generator 4. At this time, the electric generator 4 changes from the power generation state to the drive state and continues to drive the induced draft fan 8. The high-voltage grid-connected power distribution device keeps the power grid and the electric generator 4 connected at all times. The drive and power generation states of the electric generator 4 can both be kept online, thereby meeting the independent operation of the induced draft fan 8 and ensuring the smooth discharge of low-temperature flue gas.

[0031] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. This application is not limited to the exact structures described above and illustrated in the accompanying drawings, and it should not be considered that the specific implementation of this application is limited to these descriptions. For those skilled in the art, various changes and modifications made without departing from the concept of this application should be considered to fall within the protection scope of this application.

Claims

1. A combined low-temperature waste heat recovery system for pellet sintering, used for traction and power generation, characterized in that, include: Flue gas mixer (1) is used to mix the low-temperature flue gas from the sintering ring cooling system with the high-temperature flue gas from the pellet rotary kiln. The flue gas waste heat boiler (2) is connected to the flue gas mixer (1) and is used to convert the temperature of the mixed sintering ring cold low-temperature flue gas and the pellet rotary kiln high-temperature flue gas into low-temperature flue gas and generate superheated low-pressure steam. A high-speed steam turbine (3) is connected to the flue gas waste heat boiler (2) and is used to do work under the drive of superheated low-pressure steam. The high-speed steam turbine (3) has both traction and power generation functions; An electric generator (4) is connected to the high-speed steam turbine (3), and the electric generator (4) has both driving and power generation functions.

2. The pellet sintering low-temperature waste heat combined recovery drive and power generation system according to claim 1, characterized in that, A speed-changing clutch (5) is provided between the high-speed steam turbine (3) and the electric generator (4), and the speed-changing clutch (5) is used to change the connection state between the high-speed steam turbine (3) and the electric generator (4).

3. The pellet sintering low-temperature waste heat combined recovery drive and power generation system according to claim 1, characterized in that, It also includes a high-voltage automatic grid-connected power distribution device (6), which is connected to the electric generator (4) and is used to receive the electrical energy generated by the electric generator (4) or to supply power to the electric generator (4).

4. The pellet sintering low-temperature waste heat combined recovery drive and power generation system according to claim 1, characterized in that, It also includes a circulating cooling device (7), one end of which is connected to the high-speed steam turbine (3) and the other end is connected to the flue gas waste heat boiler (2).

5. The pellet sintering low-temperature waste heat combined recovery drive and power generation system according to claim 1, characterized in that, It also includes an induced draft fan (8), which is connected to the flue gas waste heat boiler (2) for discharging low-temperature flue gas.

6. The pellet sintering low-temperature waste heat combined recovery drive and power generation system according to claim 5, characterized in that, The induced draft fan (8) is connected to the electric generator (4), and the electric generator (4) is used to drive the induced draft fan (8) to discharge low-temperature flue gas.

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