A high-parameter combined cycle super-generation wet cooling unit and its operation method

Abstract

The invention discloses a high-parameter combined cycle over-generation wet-cooling unit and an operation method thereof, wherein the unit comprises a combined cycle power generation system and an existing steam turbine generator set, wherein the power output ends of the combined cycle power generation system and the existing steam turbine generator set are both connected to a power grid, and the high-pressure water supply of the existing steam turbine generator set is divided into two routes, wherein one route is connected to the water supply of the combined cycle power generation system, and the other route is connected to the water supply of the existing steam turbine generator set; the exhaust port of the combined cycle power generation system is connected to the steam turbine of the existing steam turbine generator set, and the existing steam turbine generator set is a wet-cooling unit; over-generation is achieved by assisting a large machine with the high-parameter combined cycle power generation system, thereby increasing the means and ability of the wet-cooling unit to generate power beyond the rated capacity, and improving the economy of the unit operation; reducing the fluctuation frequency of the steam inlet regulating valve of the steam turbine of the wet-cooling unit, and improving the safety of the unit operation; the system has high reliability, flexible operation, simple operation, and strong availability.

Description

Technical Field

[0001] The invention belongs to the field of power station boiler and steam turbine systems, and in particular relates to a high-parameter combined cycle super-generation wet cooling unit and an operation method thereof. Background Art

[0002] With the rapid growth of installed capacity of new energy (photovoltaic, wind power), the peak and frequency regulation tasks of thermal power units have become prominent. Grid-connected thermal power companies are under increasing assessment pressure when the AGC load instructions of the power grid change frequently. The load regulation capacity of the unit has decreased, and the actual load cannot keep up with the AGC instructions, resulting in unstable boiler combustion and drastic changes in the main and reheat steam temperatures, which have a great impact on the safe and stable operation of the equipment. Wet cooling units account for a large proportion of coal-fired power generation units due to their low cost, low back pressure, and good operating economy. Therefore, increasing the short-term over-generation capacity and response speed of wet cooling units is of great significance to optimizing the operating economy and safety of wet cooling units in future high-frequency and wide-load scenarios. Summary of the invention

[0003] In order to solve the problems existing in the prior art, the present invention provides a high-parameter combined cycle over-generation wet cooling unit and an operation method thereof. The wet cooling unit can be equipped with a high-parameter combined cycle boiler, a combined cycle steam turbine and a small generator system to assist the unit in achieving rapid load increase and timely responding to the instructions of the AGC, thereby increasing the means and ability of the wet cooling unit to generate electricity in excess of the rated capacity, reducing the fluctuation frequency of the main steam valve of the steam turbine, and having huge energy-saving potential.

[0004] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a high-parameter combined cycle super-generation wet cooling unit, including a combined cycle power generation system and an existing steam turbine generator set, the power output ends of the combined cycle power generation system and the existing steam turbine generator set are both connected to the power grid, and the high-pressure water supply of the existing steam turbine generator set is divided into two routes, one water supply is connected to the water supply of the combined cycle power generation system, and the other water supply is connected to the water supply of the existing steam turbine generator set; the exhaust port of the combined cycle power generation system is connected to the steam turbine of the existing steam turbine generator set, and the existing steam turbine generator set is a wet cooling unit.

[0005] The combined cycle power generation system includes a high-parameter combined cycle boiler, a high-parameter combined cycle steam turbine and a combined cycle generator which are connected in sequence; the output end of the combined cycle generator is connected to the power grid.

[0006] A combined cycle steam turbine steam inlet regulating valve is provided on the steam pipe in front of the inlet of the high-parameter combined cycle steam turbine.

[0007] Pressure and temperature transmitters are installed at the steam inlet and outlet of the high-parameter combined cycle steam turbine; pressure and temperature transmitters are installed at the inlet of the high-parameter combined cycle boiler.

[0008] The exhaust port of the high-parameter combined cycle steam turbine is connected to the low-pressure cylinder steam inlet of the steam turbine of the existing steam turbine generator set, and a regulating valve is arranged on the pipeline from the exhaust port of the high-parameter combined cycle steam turbine to the low-pressure cylinder steam inlet of the steam turbine of the existing steam turbine generator set.

[0009] A regulating valve is arranged on the pipeline from the high-pressure feed water outlet of the existing steam turbine generator set to the high-pressure feed water inlet of the combined cycle power generation system.

[0010] The unit steam inlet flow rate of the combined cycle power generation system shall not exceed the maximum margin of the design steam inlet flow rate of the low-pressure cylinder of the air-cooled unit, which is generally 10% of the design steam inlet flow rate of the low-pressure cylinder.

[0011] As another aspect of the present invention, the high-parameter combined cycle over-generation wet cooling unit of the present invention is used to bear the over-generation load in a power grid equipped with a new energy power supply system.

[0012] The operating method of the high-parameter combined cycle super-generation wet-cooling unit described in the present invention is that the high-pressure feed water of the existing steam turbine generator set is divided into two parts, one part goes to the boiler of the existing steam turbine generator set, and the other part goes to the high-parameter combined cycle boiler and the high-parameter combined cycle steam turbine. The exhaust steam of the high-parameter combined cycle steam turbine is directly discharged into the stage group with similar parameters of the existing steam turbine generator set to continue to generate power. The exhaust steam temperature of the high-parameter combined cycle steam turbine is higher than the temperature of the steam turbine in the existing steam turbine generator set at the exhaust inlet, thereby increasing the steam temperature of the steam turbine to achieve super-generation of the steam turbine. At the same time, the high-parameter combined cycle steam turbine also generates power. The high-parameter combined cycle power generation system assists the large steam turbine in responding to the instructions of the AGC to meet the regulation needs of the power grid.

[0013] Compared with the prior art, the present invention has at least the following beneficial effects:

[0014] (1) The high-parameter combined cycle power generation system is used to assist large units in achieving over-generation, which increases the means and capabilities of wet-cooling units to generate electricity in excess of rated capacity and improves the economic efficiency of unit operation.

[0015] (2) The fluctuation frequency of the steam inlet regulating valve of the steam turbine of the wet cooling unit is reduced, thereby improving the safety of the unit operation.

[0016] (3) The high-parameter combined cycle power generation system has high reliability, flexible operation, simple operation and strong availability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1It is a schematic diagram of a high-parameter combined cycle super-generation wet cooling unit and an operation method thereof of the present invention; in the figure, 1, a high-parameter combined cycle boiler, 2, a combined cycle steam turbine steam inlet regulating valve, 3, a high-parameter combined cycle steam turbine, 4, a combined cycle generator, 5, a boiler, 6, a steam turbine steam inlet regulating valve, 7, a steam turbine, 8, a generator, 9, a power grid, 10, a power user, 11, a feed water pump, 12, a condenser, 13, a circulating water pump, 14, a natural ventilation cooling tower. DETAILED DESCRIPTION

[0018] The preferred implementation examples of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred implementation examples described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0019] The present invention adds a high-parameter combined cycle machine, a furnace and a small generator system thereof. The final feed water of the large machine is divided into two parts, one part goes to the boiler, and the other part goes to the high-parameter combined cycle boiler and its steam turbine system. The exhaust steam of the high-parameter combined cycle steam turbine is directly discharged into the stage group with similar parameters of the large steam turbine to continue to generate power. The exhaust steam temperature of the high-parameter combined cycle steam turbine is higher than the temperature of the large steam turbine at the exhaust inlet. After mixing, the steam temperature of the large steam turbine will be increased to realize the super-generation capacity of the large steam turbine. At the same time, the high-parameter combined cycle steam turbine also generates power. The high-parameter combined cycle power generation system assists the large steam turbine in responding to the instructions of AGC to meet the regulation needs of the power grid.

[0020] refer to Figure 1 A high-parameter combined cycle super-generation wet cooling unit includes a combined cycle power generation system and an existing steam turbine generator set. The power output ends of the combined cycle power generation system and the existing steam turbine generator set are both connected to the power grid 9. The high-pressure water supply of the existing steam turbine generator set is divided into two routes, one of which is connected to the water supply of the combined cycle power generation system, and the other is connected to the water supply of the existing steam turbine generator set; the exhaust port of the combined cycle power generation system is connected to the steam turbine of the existing steam turbine generator set, and the existing steam turbine generator set is a wet cooling unit. In the existing steam turbine generator set, the feed water pump 11 delivers the feed water to the high-parameter combined cycle boiler 1 and the boiler 5. The steam of the boiler 5 enters the steam turbine 7 through the steam turbine inlet regulating valve 6 to generate electricity. The steam after work is discharged into the condenser 12 for cooling and then enters the high-pressure feed water circulation; the steam turbine 7 drives the generator 8 to generate electricity and is connected to the power grid 9, and then the power grid 9 supplies the electricity to the power user 10; the cooling water of the condenser 12 is pressurized and transported to the natural ventilation cooling tower 14 for cooling by the circulating water pump.

[0021] The combined cycle power generation system comprises a high-parameter combined cycle boiler 1 , a high-parameter combined cycle steam turbine 3 and a combined cycle generator 4 which are connected in sequence; the output end of the combined cycle generator 4 is connected to a power grid 9 .

[0022] A combined cycle steam turbine steam inlet regulating valve 2 is provided on the steam pipeline before the inlet of the high parameter combined cycle steam turbine 3 .

[0023] Pressure and temperature transmitters are provided at the steam inlet and outlet of the high-parameter combined cycle steam turbine 3 ; and pressure and temperature transmitters are provided at the inlet of the high-parameter combined cycle boiler 1 .

[0024] The exhaust port of the high-parameter combined cycle steam turbine 3 is connected to the low-pressure cylinder steam inlet of the steam turbine of the existing steam turbine generator set, and a regulating valve is arranged on the pipeline from the exhaust port of the high-parameter combined cycle steam turbine 3 to the low-pressure cylinder steam inlet of the steam turbine of the existing steam turbine generator set.

[0025] A regulating valve is arranged on the pipeline from the high-pressure feed water outlet of the existing steam turbine generator set to the high-pressure feed water inlet of the combined cycle power generation system.

[0026] The unit steam inlet flow of the combined cycle power generation system does not exceed the maximum margin of the design steam inlet flow of the low-pressure cylinder of the air-cooled unit, and the steam inlet flow is generally 10% of the design steam inlet flow of the low-pressure cylinder.

[0027] The high-parameter combined cycle over-generation wet cooling unit of the present invention is used to bear the over-generation load in a power grid equipped with a new energy power supply system.

[0028] According to the operation method of the high-parameter combined cycle super-generation wet cooling unit of the present invention, the high-pressure feed water of the existing steam turbine generator set is divided into two parts, one part goes to the boiler 5 of the existing steam turbine generator set, and the other part goes to the high-parameter combined cycle boiler 1 and the high-parameter combined cycle steam turbine 3. The exhaust steam of the high-parameter combined cycle steam turbine 3 is directly discharged into the stage group with similar parameters of the existing steam turbine generator set to continue to generate power. The exhaust steam temperature of the high-parameter combined cycle steam turbine 3 is higher than the temperature of the steam turbine in the existing steam turbine generator set at the exhaust inlet, which increases the temperature of the subsequent steam of the steam turbine and realizes the super-generation of the steam turbine. At the same time, the high-parameter combined cycle steam turbine 2 also generates power. The high-parameter combined cycle power generation system assists the large steam turbine in responding to the instructions of AGC to meet the regulation needs of the power grid.

[0029] For explanation, the large unit and large steam turbine described in the present application correspond to existing steam turbine generator sets, and the small unit corresponds to high-parameter combined cycle system steam turbine units.

[0030] The existing steam turbine generator set is any one of 300 to 1000MW class sets.

[0031] Implementation Example 1

[0032] A 330MW subcritical, one-stage intermediate reheat, double-cylinder double-exhaust, single-shaft, condensing steam turbine generator set, unit model N310-16.7 / 538 / 538, under VWO conditions, main steam pressure 16.7MPa, main steam temperature 538℃, reheat steam temperature 538℃, low-pressure cylinder inlet steam pressure 0.802MPa, low-pressure cylinder inlet steam temperature 347.067℃. Against the backdrop of the growth of installed capacity of new energy (photovoltaic, wind power), the peak-shaving and frequency-regulating tasks of thermal power units have become prominent. With the implementation of the "two detailed rules" ("Implementation Rules for Auxiliary Service Management of Grid-connected Power Plants" and "Implementation Rules for Grid-connected Operation Management of Power Plants") of the provincial power grid company, the grid dispatching department has increased the assessment of the operation quality of AGC (automatic power generation control, i.e., automatic control of power system frequency and active power) of its grid-connected power generation enterprises. In this case, the grid-connected thermal power enterprises are subject to increased assessment pressure when the grid AGC load instructions change frequently. The load regulation capability of the unit decreased, and the actual load could not keep up with the AGC instructions, resulting in unstable boiler combustion and drastic changes in the main and reheat steam temperatures, which had a great impact on the safe and stable operation of the equipment.

[0033] A high-parameter combined cycle wet-cooled unit over-generation process and implementation system is now implemented for the unit. A high-parameter combined cycle steam turbine, boiler and its small generator system are added. The final feed water of the large unit is divided into two parts, one part goes to the boiler, and the other part goes to the high-parameter combined cycle boiler and its steam turbine system. The exhaust steam of the high-parameter combined cycle steam turbine is directly discharged into the stage group with similar parameters of the large steam turbine to continue to generate power. The exhaust temperature of the high-parameter combined cycle steam turbine is higher than the temperature of the large steam turbine at the exhaust inlet. After mixing, the steam temperature of the large steam turbine will be increased to achieve over-generation of the large steam turbine. At the same time, the high-parameter combined cycle steam turbine also generates power. The high-parameter combined cycle power generation system assists the large steam turbine to respond to the instructions of the AGC to meet the regulation needs of the power grid, improve the economy of the unit operation, and at the same time, reduce the fluctuation frequency of the steam inlet regulating valve of the wet-cooled unit steam turbine, and improve the safety of the unit operation. The high-parameter combined cycle power generation system has high reliability, flexible operation, simple operation and strong availability.

[0034] The exhaust pipe of the high-parameter combined cycle steam turbine is connected to the medium- and low-pressure connecting pipes for mixing, and then enters the low-pressure cylinder to continue to work. The steam intake of the high-parameter combined cycle steam turbine can be adjusted according to the operation needs.

[0035] Table 1 shows the operating parameters of the high-parameter combined cycle power generation system under the THA condition of the large steam turbine. It can be seen from Table 1 that when the steam inlet of the high-parameter combined cycle steam turbine is 30t / h, the combined cycle power generation system can generate 4.675MW of electricity, the large steam turbine over-generated 6.31MW, and the total over-generated power is 10.985MW; when the steam inlet of the high-parameter combined cycle steam turbine is 60t / h, the combined cycle power generation system can generate 9.559MW of electricity, the large steam turbine over-generated 11.818MW, and the total over-generated power is 21.377MW.

[0036] Table 1 Operating parameters of high-parameter combined cycle power generation system under large steam turbine THA condition

[0037]

[0038] Overproduction process of wet cooling unit in high-parameter combined cycle and operation mode of implementation system:

[0039] When the load of the power grid 9 increases and fluctuates or the power supply of new energy (wind power, photovoltaic) decreases and the thermal power units need to over-generate, the high-parameter combined cycle power generation system cooperates with the steam turbine 7 to participate in peak load and frequency regulation according to the needs of the power grid 9. By adjusting the opening of the combined cycle steam turbine steam inlet regulating valve 2, the overall output of the high-parameter combined cycle steam turbine 3 and the steam turbine 7 is adjusted to meet the scheduling needs of the power grid 9.

Claims

1. A high-parameter combined cycle super-generation wet cooling unit, characterized in that: The invention comprises a combined cycle power generation system and an existing steam turbine generator set, wherein the power output ends of the combined cycle power generation system and the existing steam turbine generator set are both connected to a power grid (9), and the high-pressure water supply of the existing steam turbine generator set is divided into two routes, one of which is connected to the water supply of the combined cycle power generation system and the other is connected to the water supply of the existing steam turbine generator set; the exhaust port of the combined cycle power generation system is connected to the steam turbine of the existing steam turbine generator set, and the existing steam turbine generator set is a wet cooling unit; the combined cycle power generation system comprises a high-parameter combined cycle boiler (1), a high-parameter combined cycle steam turbine (3) and a combined cycle generator (4) which are connected in sequence; the output end of the combined cycle generator (4) is connected to the power grid (9); the high-parameter combined cycle steam turbine (3) and the combined cycle generator (4) are ... The exhaust port of the combined cycle steam turbine (3) is connected to the steam inlet of the low-pressure cylinder of the steam turbine of the existing steam turbine generator set, and a regulating valve is arranged on the pipeline from the exhaust port of the high-parameter combined cycle steam turbine (3) to the steam inlet of the low-pressure cylinder of the steam turbine of the existing steam turbine generator set; the steam inlet flow of the combined cycle power generation system does not exceed the maximum margin of the designed steam inlet flow of the low-pressure cylinder of the wet cooling unit, and the steam inlet flow is 10% of the designed steam inlet flow of the low-pressure cylinder; the steam temperature of the steam turbine is increased to achieve over-generation of the steam turbine, and at the same time, the high-parameter combined cycle steam turbine (3) also performs work to generate electricity, and the high-parameter combined cycle power generation system assists the large steam turbine in responding to the command of the AGC to meet the regulation requirements of the power grid.

2. The high-parameter combined cycle super-generation wet cooling unit according to claim 1 is characterized in that: A combined cycle steam turbine steam inlet regulating valve (2) is provided on a steam pipeline in front of an inlet of a high-parameter combined cycle steam turbine (3).

3. The high-parameter combined cycle super-generation wet cooling unit according to claim 1 is characterized in that: Pressure and temperature transmitters are provided at the steam inlet and outlet of the high-parameter combined cycle steam turbine (3); and pressure and temperature transmitters are provided at the inlet of the high-parameter combined cycle boiler (1).

4. The high-parameter combined cycle super-generation wet cooling unit according to claim 1 is characterized in that: A regulating valve is arranged on the pipeline from the high-pressure feed water outlet of the existing steam turbine generator set to the high-pressure feed water inlet of the combined cycle power generation system.

5. Application of the high-parameter combined cycle super-generation wet cooling unit according to any one of claims 1 to 4, characterized in that: Used to bear excess load in power grids equipped with renewable energy power supply systems.

6. The method for operating the high-parameter combined cycle super-generation wet cooling unit according to any one of claims 1 to 4, characterized in that: The high-pressure feed water of the existing steam turbine generator set is divided into two parts, one part goes to the boiler (5) of the existing steam turbine generator set, and the other part goes to the high-parameter combined cycle boiler (1) and the high-parameter combined cycle steam turbine (3). The exhaust steam of the high-parameter combined cycle steam turbine (3) is directly discharged into the low-pressure cylinder of the steam turbine of the existing steam turbine generator set to continue to generate power. The exhaust steam temperature of the high-parameter combined cycle steam turbine (3) is higher than the temperature of the steam turbine in the existing steam turbine generator set at the exhaust inlet, thereby increasing the steam temperature of the steam turbine to achieve over-generation of the steam turbine. At the same time, the high-parameter combined cycle steam turbine (3) also generates power. The high-parameter combined cycle power generation system assists the large steam turbine in responding to the command of the AGC to meet the regulation requirements of the power grid.

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