A high-parameter combined cycle over-firing air-cooled unit and its operation method

Abstract

The present invention discloses a high-parameter combined cycle over-firing air-cooled unit and its operation method. The unit includes an existing steam turbine generator set and a combined cycle power generation system. The combined cycle power generation system and the existing steam turbine generator set are connected to the same feed water outlet. The exhaust outlet of the combined cycle power generation system is connected to the inlet of the low-pressure cylinder of the main steam turbine of the existing steam turbine generator set. The electric energy outputs of the existing steam turbine generator set and the combined cycle power generation system are both connected to the power grid. The existing steam turbine generator set is an air-cooled unit. By using the high-parameter combined cycle system to assist the air-cooled unit to achieve over-firing, the means and ability of the air-cooled unit to generate electricity beyond the rated power are increased, and the economic efficiency of the operation of the air-cooled unit is improved. The fluctuation frequency of the steam inlet control valve of the steam turbine of the air-cooled unit is reduced, and the operation safety of the air-cooled unit is improved. The high-parameter combined cycle high back-pressure steam turbine generator system has high reliability, flexible operation and simple operation.

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 air-cooling unit and an operation method thereof. Background Art

[0002] With the rapid growth of installed capacity of new energy (photovoltaic, wind power), the power generation of new energy (photovoltaic, wind power) is intermittent and unstable, and the short-term over-generation task of thermal power units is prominent. When the AGC load instructions of the power grid change frequently, the assessment pressure of thermal power companies connected to the grid increases. The load regulation ability of the unit decreases, 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 has a great impact on the safe and stable operation of the equipment.

[0003] With the gradual improvement of direct air cooling and indirect air cooling technology, the initial parameters and capacity of air-cooled units have gradually increased. In view of the water-saving performance of air-cooled units, in areas with "rich coal and lack of water", it has become one of the mainstream units for the construction of thermal power units in recent years. Therefore, increasing the over-generation capacity and load response speed of air-cooled units is of great significance to the optimization of the economic and safety of air-cooled units in future high-frequency and wide-load scenarios. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a high-parameter combined cycle over-generation air-cooled unit and an operation method thereof. A high-parameter combined cycle high back-pressure steam turbine generator system can be added to the direct air-cooled unit to assist the large unit in generating electricity over rated load, thereby increasing the over-generation capacity and means of the direct air-cooled unit, and improving the regulation efficiency and regulation safety of the direct air-cooled unit in future high-frequency and wide-load application scenarios, with huge energy-saving potential.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a high-parameter combined cycle super-generation air-cooled unit, including an existing steam turbine generator set and a combined cycle power generation system, the combined cycle power generation system and the existing steam turbine generator set are connected to the same water supply outlet, the exhaust outlet of the combined cycle power generation system is connected to the main steam turbine of the existing steam turbine generator set, and the electric energy outputs of the existing steam turbine generator set and the combined cycle power generation system are both connected to the power grid; the existing steam turbine generator set is an air-cooled unit.

[0006] The combined cycle power generation system includes a high-parameter combined cycle boiler, a high-parameter combined cycle high back pressure steam turbine and a combined cycle generator which are connected in sequence; the exhaust port of the combined cycle generator is connected to the steam inlet of the steam turbine, and the inlet of the high-parameter combined cycle boiler is connected to the feed water outlet.

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

[0008] The exhaust port of the high-parameter combined cycle high back-pressure steam turbine is connected to the inlet of the low-pressure cylinder in the main steam turbine.

[0009] A regulating valve, pressure and temperature transmitters are arranged on the pipeline from the exhaust steam outlet of the combined cycle power generation system to the main steam turbine of the existing steam turbine generator set.

[0010] A regulating valve is provided on the pipeline from the feed water outlet to the inlet of the high-parameter combined cycle boiler.

[0011] The steam inlet flow rate of the unit of the combined cycle power generation system does not exceed the maximum margin of the designed steam inlet flow rate of the low-pressure cylinder of the air-cooled unit, and the steam inlet flow rate is 10% of the designed steam inlet flow rate of the low-pressure cylinder. The application of the high-parameter combined cycle super-generation air-cooled unit of the present invention is used to respond to the super-generation command of the power grid.

[0012] The operating method of the high-parameter combined cycle over-generation air-cooled unit described in the present invention is that when the load of the power grid increases or the power supply of new energy decreases, and over-generation of thermal power units is required, the high-parameter combined cycle system cooperates with the existing steam turbine generator sets to participate in over-generation according to the needs of the power grid, and increases the steam intake of the turbine in the combined cycle power generation system to adjust the output of the turbine in the combined cycle power generation system to meet the scheduling 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 system is used to assist the air-cooled unit in achieving over-generation, which increases the means and capabilities of the air-cooled unit to generate power in excess of the rated power and improves the economic efficiency of the air-cooled unit operation.

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

[0016] (3) The high-parameter combined cycle high back-pressure steam turbine generator system has high reliability, flexible operation and simple operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of a high-parameter combined cycle super-generating air-cooling unit of the present invention;

[0018] In the figure, 1. high-parameter combined cycle boiler, 2. combined cycle high back-pressure steam turbine steam inlet regulating valve, 3. high-parameter combined cycle high back-pressure steam turbine, 4. combined cycle generator, 5. main boiler, 6. main steam turbine steam inlet regulating valve, 7. main steam turbine, 8. main generator, 9. power grid, 10. various power users, 11. feed water pump, 12. air cooling island, 13. fan. DETAILED DESCRIPTION

[0019] 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.

[0020] refer to Figure 1 A high-parameter combined cycle super-generating air-cooled unit comprises an existing steam turbine generator set and a combined cycle power generation system. The combined cycle power generation system and the existing steam turbine generator set are connected to the same feedwater outlet. The exhaust outlet of the combined cycle power generation system is connected to the main steam turbine 7 of the existing steam turbine generator set. The power outputs of the existing steam turbine generator set and the combined cycle power generation system are both connected to the power grid 9. The existing steam turbine generator set is an air-cooled unit. The feedwater pump 11 of the existing steam turbine generator set delivers high-pressure feedwater to the high-parameter combined cycle boiler 1 and the main boiler 5. The steam from the boiler 5 enters the main steam turbine 7 through the main steam turbine steam inlet regulating valve 6 to perform work. The steam after performing work enters the air cooling island 12 for air cooling. During the air cooling process, a fan 13 is used to enhance the heat exchange efficiency. The main steam turbine 7 drives the main generator 8 to generate electricity and is connected to the power grid 9. The electric energy is supplied to various power users 10 through the power grid; the feed water entering the high-parameter combined cycle boiler 1 forms high-parameter steam, which enters the high-parameter combined cycle high back-pressure steam turbine 3 through the combined cycle high back-pressure steam inlet regulating valve 2 to perform work, driving the combined cycle generator 4 to generate electricity and be connected to the power grid 9.

[0021] The combined cycle power generation system includes a high-parameter combined cycle boiler 1, a high-parameter combined cycle high back pressure steam turbine 3 and a combined cycle generator 4 which are connected in sequence; the exhaust port of the combined cycle generator 4 is connected to the steam inlet of the steam turbine 7, and the inlet of the high-parameter combined cycle boiler 1 is connected to the feed water outlet.

[0022] Pressure and temperature transmitters are provided at the steam inlet of the high-parameter combined cycle high back-pressure steam turbine 3.

[0023] The exhaust port of the high-parameter combined cycle high back-pressure steam turbine 3 is connected to the low-pressure cylinder inlet of the steam turbine 7.

[0024] A regulating valve, pressure and temperature transmitters are provided on the pipeline from the exhaust steam outlet of the combined cycle power generation system to the main steam turbine 7 of the existing steam turbine generator set.

[0025] A regulating valve is provided on the pipeline from the feed water outlet to the inlet of the high-parameter combined cycle boiler 1 .

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

[0027] The application of the high-parameter combined cycle super-generation air-cooling unit described in the present invention is used to respond to the super-generation instruction of the power grid.

[0028] The existing steam turbine generator set is any one of the 300~1000MW units

[0029] Implementation Example 1

[0030] The NZK600-24.2 / 566 / 566 supercritical, single intermediate reheat, single shaft, three-cylinder four-exhaust, direct air-cooled condensing steam turbine unit manufactured by Dongfang Steam Turbine Co., Ltd. has a main steam pressure of 24.2MPa, a main steam temperature of 566℃, a reheat steam temperature of 566℃, a low-pressure cylinder inlet steam pressure of 1.06MPa, and an inlet steam enthalpy of 3193.4kJ / kg under THA conditions. In recent years, under the background of the growth rate of installed capacity of new energy (photovoltaic, wind power), due to the intermittent and unstable nature of new energy (photovoltaic, wind power), the short-term over-generation task of thermal power units has become prominent. In this case, when the AGC load instructions of the power grid change frequently, the assessment pressure of the grid-connected thermal power companies increases. The load regulation capacity of the unit decreases, 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 has a great impact on the safe and stable operation of the equipment.

[0031] A high-parameter combined cycle super-generation air-cooled unit is now implemented for the unit, and a high-parameter combined cycle boiler, a high-parameter combined cycle high back-pressure steam turbine and its generator system are added. A part of the feed water of the main boiler is separated to the high-parameter combined cycle boiler and its steam turbine system. The exhaust steam of the high-parameter combined cycle high back-pressure steam turbine is directly discharged into the low-pressure cylinder inlet of the main steam turbine of the direct air-cooled unit 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 achieve super-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 system assists the large steam turbine to respond to the instructions of the AGC to meet the needs of the power grid and improve the economy of the unit operation. At the same time, the fluctuation frequency of the steam inlet regulating valve of the air-cooled unit steam turbine is reduced, and the safety of the air-cooled unit operation is improved. The high-parameter combined cycle system is used to assist the air-cooled unit in achieving over-generation, which increases the means and capabilities of the air-cooled unit to generate electricity in excess of the rated power and improves the economic efficiency of the air-cooled unit operation; reduces the fluctuation frequency of the steam inlet regulating valve of the air-cooled unit turbine and improves the safety of the air-cooled unit operation; the high-parameter combined cycle high back-pressure steam turbine generator system has high reliability, flexible operation and simple operation.

[0032] Under VWO working condition, the steam inlet pressure of the high-parameter combined cycle steam turbine is 5MPa, the steam inlet temperature is 800℃, the exhaust temperature is 552.542℃, and the exhaust pipe of the high-parameter combined cycle steam turbine is connected to the medium- and low-pressure connecting pipe, and enters the low-pressure cylinder to continue to work. The steam inlet volume of the high-parameter combined cycle steam turbine can be adjusted according to the operation needs.

[0033] Table 1 shows the operating parameters of the high-parameter combined cycle system under THA conditions of the direct air-cooled unit. 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 system can generate 4.586MW of electricity, the large steam turbine over-generates 5.127MW, and the total over-generation power is 9.713MW; when the steam inlet of the high-parameter combined cycle steam turbine is 65t / h, the combined cycle system can generate 9.786MW of electricity, the large steam turbine over-generates 11.244MW, and the total over-generation power is 21.03MW; when the steam inlet of the high-parameter combined cycle steam turbine is 130t / h, the combined cycle system can generate 19.028MW of electricity, the large steam turbine over-generates 22.946MW, and the total over-generation power is 41.974MW.

[0034] Table 1 Operating parameters of high-parameter combined cycle system of direct air-cooled unit under THA condition

[0035]

[0036] Operation mode of high parameter combined cycle super power air cooling unit:

[0037] When the load of the power grid 9 increases 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 system cooperates with the steam turbine 7 to participate in the over-generation 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 output of the high-parameter combined cycle steam turbine 3 is adjusted to meet the scheduling needs of the power grid 9.

Claims

1. A high-parameter combined cycle over-firing air-cooled unit, characterized in that, it includes an existing steam turbine generator set and a combined cycle power generation system. The combined cycle power generation system and the existing steam turbine generator set are connected to the same feed water outlet. The exhaust steam outlet of the combined cycle power generation system is connected to the main steam turbine (7) of the existing steam turbine generator set. The electric energy outputs of the existing steam turbine generator set and the combined cycle power generation system are both connected to the power grid (9); the existing steam turbine generator set is an air-cooled unit; the combined cycle power generation system includes a high-parameter combined cycle boiler (1), a high-parameter combined cycle high back-pressure steam turbine (3), and a combined cycle generator (4) connected in sequence; the exhaust steam outlet of the combined cycle generator (4) is communicated with the steam inlet of the main steam turbine (7), and the inlet of the high-parameter combined cycle boiler (1) is connected to the feed water outlet; a pressure and temperature transmitter is arranged at the steam inlet of the high-parameter combined cycle high back-pressure steam turbine (3); the exhaust steam outlet of the high-parameter combined cycle high back-pressure steam turbine (3) is connected to the inlet of the low-pressure cylinder in the main steam turbine (7); a regulating valve, a pressure and temperature transmitter are arranged on the pipeline from the exhaust steam outlet of the combined cycle power generation system to the main steam turbine (7) of the existing steam turbine generator set; the steam inlet flow rate of the combined cycle power generation system unit does not exceed the maximum margin of the designed steam inlet flow rate of the low-pressure cylinder of the air-cooled unit, and the inlet flow rate is 10% of the designed steam inlet flow rate of the low-pressure cylinder.

2. The high-parameter combined cycle over-firing air-cooled unit according to claim 1, characterized in that, a regulating valve is arranged on the pipeline from the feed water outlet to the inlet of the high-parameter combined cycle boiler (1).

3. The application of the high-parameter combined cycle over-firing air-cooled unit according to any one of claims 1-2, characterized in that, it is used to respond to the over-firing instruction of the power grid.

4. The operation method of the high-parameter combined cycle over-firing air-cooled unit according to any one of claims 1-2, characterized in that, when the load of the power grid (9) increases or the power supply of new energy decreases and the thermal power unit needs to over-fire, the high-parameter combined cycle system cooperates with the existing steam turbine generator set to participate in over-firing according to the needs of the power grid (9). By increasing the steam inlet flow rate of the steam turbine in the combined cycle power generation system, the output of the steam turbine in the combined cycle power generation system is adjusted to meet the dispatching requirements of the power grid (9).

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