Coal-fired unit power generation system

Abstract

The utility model discloses a coal-fired unit power generation system which is provided with a steam turbine used for generating power, an output shaft of the steam turbine is connected with a power generator and provides power generation kinetic energy for the power generator, the steam turbine is provided with a steam inlet and an air supply connector, and the steam inlet is connected with a high-pressure steam source through a pipeline provided with a high-pressure steam control valve. The air supply connector is connected with a low-pressure steam source through a pipeline provided with a low-pressure air supply control valve. According to the utility model, the power generation efficiency of the coal-fired unit can be improved, an existing coal-fired unit is technically improved, a secondary steam extraction system of a steam turbine is changed into a steam supplementing system, low-temperature and low-pressure waste heat steam in a plant is used for supplementing steam for the coal-fired unit, and the steam inlet flow of high-temperature and high-pressure steam is reduced according to the law of conservation of energy; therefore, the use amount of coal is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of coal-fired power generation. Background Art

[0002] The main fuel for high-temperature and high-pressure coal-fired units comes from coal. Currently, the basic configuration of high-temperature and high-pressure coal-fired units is a steam extraction system, which basically meets the normal operation requirements. However, the fuel is single, the power generation efficiency of the coal-fired units is low, and the economic benefits are poor.

[0003] Therefore, there are currently many power generation systems that combine other energy supply methods, such as the public document with announcement number CN207673388U, publication date 2018-07-31, and patent name "A high-efficiency utilization system for biomass-coupled coal-fired units", which discloses a high-efficiency utilization system for biomass-coupled coal-fired units, involving renewable energy utilization technologies such as biomass and coal-fired boiler power generation, including direct-fired boilers, coal-fired power generation boilers and coal-fired boiler reheater systems. The steam generated by the direct-fired boiler is sent to the high-temperature reheater inlet of the coal-fired boiler reheater system of the coal-fired power generation boiler through a steam pipeline and continues to be heated.

[0004] Similar coal-fired power plants simply use high-temperature and high-pressure steam to generate electricity. The steam turbine units are not equipped with an automatic low-temperature and low-pressure steam replenishment system, nor are they equipped with a steam replenishment automatic coordination control system. It is impossible to use the low-temperature and low-pressure waste heat steam in the plant to automatically replenish steam for the units, resulting in a single steam source for high-temperature and high-pressure unit projects, large coal consumption, high costs, and poor economic benefits.

[0005] An automatic coordinated control system for supplementary steam is added to the DCS and DEH to realize automatic control of the supplementary steam switch valve and the supplementary steam regulating valve, and at the same time realize automatic coordinated control of low-temperature and low-pressure supplementary steam and high-temperature and high-pressure main steam, ensuring the stable operation of the coal-fired units and improving the power generation efficiency of the coal-fired units. Utility Model Content

[0006] The technical problem to be solved by the utility model is to realize a power generation system configured with an automatic low-temperature and low-pressure steam supplement system for a steam turbine unit, so as to improve the unit efficiency of the power generation system.

[0007] In order to achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a coal-fired unit power generation system, the system is provided with a steam turbine for power generation, the output shaft of the steam turbine is connected to a generator and provides power generation energy for the generator, the steam turbine is provided with a steam inlet and an air supply interface, the steam inlet is connected to a high-pressure steam source through a pipeline provided with a high-pressure steam regulating valve, and the air supply interface is connected to a low-pressure steam source through a pipeline provided with a low-pressure air supply regulating valve.

[0008] The high-pressure steam gas source is high-pressure steam generated by a coal-fired engine.

[0009] The low-pressure steam gas source is steam generated by a waste heat boiler.

[0010] The low-pressure steam source as one of the power domains of the steam turbine has an output accounting for less than half of the total load.

[0011] The power generation system is provided with a DCS control system. The steam inlet and the air supply interface are both provided with air pressure sensors. The two air pressure sensors are connected and output air pressure signals to the DCS control system. The DCS control system is connected and outputs control signals to the high-pressure steam regulating valve and the low-pressure air supply regulating valve.

[0012] The DCS control system is connected to and outputs control signals to the coal-fired machine.

[0013] The power output end of the generator is connected to the power grid.

[0014] A control method based on the coal-fired unit power generation system obtains the steam pressure of the steam inlet and the air supply interface in real time, performs PID control according to the set air intake pressure, and adjusts the high-pressure steam regulating valve and the low-pressure air supply regulating valve respectively, so that the steam pressure input to the coal-fired machine is maintained at the set air intake pressure.

[0015] When the generator output power is stable, the set intake pressure of the steam inlet will decrease, while the set intake pressure of the air supply interface will increase to maintain the stability of the generator output power.

[0016] The utility model can improve the power generation efficiency of coal-fired units. It carries out technical transformation on existing coal-fired power generation units, changes the secondary steam extraction system of the steam turbine into a steam supplement system, utilizes the low-temperature and low-pressure waste heat steam in the plant to supplement steam for the coal-fired units, and reduces the high-temperature and high-pressure steam inlet flow rate according to the law of conservation of energy, thereby achieving the goal of reducing coal usage.

[0017] According to the operation data analysis before the waste heat boiler in the plant was put into operation (May 8 to 12, 2023), the average standard coal consumption of the coal-fired unit in continuous operation was about 332.47t / d (actual coal consumption was 590.63t / d), and the average standard coal consumption after the waste heat boiler was put into operation (August 27 to 29, 2023) was 239.60t / d (actual coal consumption was 419.88t / d), saving 92.87t / d of standard coal (actual coal consumption was 170.75t / d, due to the difference in the calorific value of actual coal before and after the comparison, there was a slight deviation from the calculated value of 162.73t / d, and the result was subject to the calculated value), and the coal saving rate reached 27.9%.

[0018] According to the comparative analysis of the actual coal consumption before and after the commissioning of the waste heat boiler in the plant, an average of about 162.73t / d of physical coal is saved. Referring to the operation rate of 81.07% of the No. 1 kiln system and 72.31% of the No. 2 kiln system in 2022, and calculated based on the local coal price of 304 yuan / ton, the annual cost savings are 13.848 million yuan, with considerable economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The following is a brief description of the contents of each figure in the utility model specification:

[0020] Figure 1 This is the schematic diagram of the power generation system of the improved coal-fired unit;

[0021] Figure 2 This is the schematic diagram of the existing coal-fired unit power generation system. DETAILED DESCRIPTION

[0022] The following is a description of the embodiments with reference to the accompanying drawings, and further detailed descriptions are given of the specific implementation methods of the present invention, such as the shapes and structures of the components involved, the relative positions and connection relationships between the components, the functions and working principles of the components, the manufacturing process and the operation and use methods, so as to help those skilled in the art to have a more complete, accurate and in-depth understanding of the utility model concept and technical solution of the present invention.

[0023] At present, the power of the generator of the coal-fired power generation system mainly comes from coal-fired high-pressure steam, and the regulation is mainly based on the grid-connected power to adjust the high-pressure steam valve, so as to control the coal consumption; the steam source is single, that is, the output shaft of the steam turbine used for power generation is connected to the generator and provides power generation energy for the generator, and the power output end of the generator is connected to the power grid to output electrical energy to the power grid stably. The steam turbine is provided with a steam inlet and an air supply interface, wherein the steam inlet is connected to the high-pressure steam source through a pipeline provided with a high-pressure steam valve, and the high-pressure steam source is generated by the coal-fired machine. The air supply interface is connected to the low-pressure steam source through a pipeline provided with a low-pressure air supply valve, and the low-pressure steam source is generated by the waste heat boiler.

[0024] The low-temperature and low-pressure steam from the waste heat boiler is used as supplementary steam for the coal-fired units, with its output accounting for less than half of the total load. It has fewer control parameters, simpler operation, and relatively stable overall operation. Through hard-wired interlocking with the main steam valve, ETS action, and OPC action of the coal-fired units, and utilizing the rapid action of the supplementary steam fast closing valve and the regulating valve, the system operates safely and reliably.

[0025] After the technical transformation, when the generator power is constant, the low-pressure steam supply adjustment pressure is set. When the low-pressure pressure and flow increase, the high-pressure steam regulating door is automatically closed, thereby reducing the evaporation of the boiler and reducing the use of coal.

[0026] The power generation system is equipped with a DCS control system, which is the control core of the entire power generation system. The steam inlet and the air supply interface are equipped with air pressure sensors. The two air pressure sensors are connected and output air pressure signals to the DCS control system. The DCS control system is connected and outputs control signals to the high-pressure steam regulating valve and the low-pressure air supply regulating valve. The DCS control system is connected and outputs control signals to the coal-fired machine.

[0027] The DCS control system collects changes in low-temperature and low-pressure supplementary steam pressure and high-temperature and high-pressure main steam pressure. At the same time, the DCS system sets a fixed steam inlet pressure for PID control. The opening size of the on-site supplementary steam regulating valve and the main steam regulating valve are automatically adjusted by PID according to the real-time pressure, thereby achieving stable generator power output. When the generator power is stable, the main steam pressure and supplementary steam pressure will be automatically adjusted. At the same time, the supplementary steam pressure increases and the generator power is constant, which will reduce the main steam pressure, thereby controlling the amount of coal burned and improving economic benefits.

[0028] During specific control, the steam pressure of the steam inlet and the air supply interface is obtained in real time, and PID control is performed according to the set intake pressure. The high-pressure steam regulating valve and the low-pressure air supply regulating valve are adjusted respectively to maintain the steam pressure input to the coal-fired machine at the set intake pressure. The set intake pressure has two sets of data, which are independently controlled by PID. Through PID automatic adjustment, the low-temperature and low-pressure steam inlet and steam supply are controlled to ensure stable operation of the unit.

[0029] This system coordinates the control of low-temperature and low-pressure steam inlet with high-temperature and high-pressure steam inlet, combines the low-temperature and low-pressure steam inlet pressure of the unit, and automatically adjusts the high-temperature and high-pressure steam inlet pressure PID according to the constant load of the unit. When the generator power is stable, the main steam pressure and the supplementary steam pressure will be automatically adjusted. At the same time, the supplementary steam pressure increases and the generator power is constant, which will reduce the main steam pressure, thereby controlling the amount of coal burned and improving economic benefits.

[0030] The purpose of the utility model is to improve the power generation efficiency of coal-fired units, to carry out technical transformation of existing coal-fired power generation units, to change the secondary extraction steam system of the steam turbine into a supplementary steam system, to use the low-temperature and low-pressure waste heat steam in the plant to supplement the coal-fired units, and to reduce the high-temperature and high-pressure steam inlet flow rate according to the law of conservation of energy, thereby reducing the use of coal. The utility model method mainly adds a supplementary steam automatic coordination control system to the DCS and DEH, realizes the automatic control of the supplementary steam switch valve and the supplementary steam regulating valve, and realizes the automatic coordination control of the low-temperature and low-pressure supplementary steam and the high-temperature and high-pressure main steam at the same time, to ensure the stable operation of the coal-fired units and improve the power generation efficiency of the coal-fired units.

[0031] The utility model is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the utility model is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the method concept and technical solution of the utility model, or the concept and technical solution of the utility model are directly applied to other occasions without improvement, they are all within the protection scope of the utility model.

Claims

1. A coal-fired unit power generation system, the system is provided with a steam turbine for power generation, the output shaft of the steam turbine is connected to a generator and provides power generation energy to the generator, the steam turbine is provided with a steam inlet and an air supply interface, the steam inlet is connected to a high-pressure steam gas source through a pipeline provided with a high-pressure steam regulating valve, characterized in that: The air supply interface is connected to a low-pressure steam gas source through a pipeline provided with a low-pressure air supply regulating valve.

2. The coal-fired unit power generation system according to claim 1, characterized in that: The high-pressure steam gas source is high-pressure steam generated by a coal-fired engine.

3. The coal-fired unit power generation system according to claim 2, characterized in that: The low-pressure steam gas source is steam generated by a waste heat boiler.

4. The coal-fired unit power generation system according to claim 3, characterized in that: The low-pressure steam source as one of the power domains of the steam turbine has an output accounting for less than half of the total load.

5. The coal-fired unit power generation system according to claim 2, 3 or 4, characterized in that: The power generation system is provided with a DCS control system. The steam inlet and the air supply interface are both provided with air pressure sensors. The two air pressure sensors are connected and output air pressure signals to the DCS control system. The DCS control system is connected and outputs control signals to the high-pressure steam regulating valve and the low-pressure air supply regulating valve.

6. The coal-fired unit power generation system according to claim 5, characterized in that: The DCS control system is connected to and outputs control signals to the coal-fired machine.

7. The coal-fired unit power generation system according to claim 1 or 6, characterized in that: The power output end of the generator is connected to the power grid.

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