CN108104887B - Thermodynamic system with double reheating - Google Patents
Thermodynamic system with double reheating Download PDFInfo
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- CN108104887B CN108104887B CN201711288319.9A CN201711288319A CN108104887B CN 108104887 B CN108104887 B CN 108104887B CN 201711288319 A CN201711288319 A CN 201711288319A CN 108104887 B CN108104887 B CN 108104887B
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- 238000003303 reheating Methods 0.000 title claims abstract description 25
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K3/00—Plants characterised by the use of steam or heat accumulators, or intermediate steam heaters, therein
- F01K3/18—Plants characterised by the use of steam or heat accumulators, or intermediate steam heaters, therein having heaters
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D15/00—Adaptations of machines or engines for special use; Combinations of engines with devices driven thereby
- F01D15/08—Adaptations for driving, or combinations with, pumps
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D15/00—Adaptations of machines or engines for special use; Combinations of engines with devices driven thereby
- F01D15/10—Adaptations for driving, or combinations with, electric generators
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K13/00—General layout or general methods of operation of complete plants
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K7/00—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating
- F01K7/34—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating the engines being of extraction or non-condensing type; Use of steam for feed-water heating
- F01K7/38—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating the engines being of extraction or non-condensing type; Use of steam for feed-water heating the engines being of turbine type
Abstract
The invention relates to the field of thermal power generation, and discloses a thermal system for secondary reheating, which comprises a steam turbine, a condenser, a bypass turbine, a hybrid drive turbine and a high-pressure heater; the steam turbine comprises an ultrahigh pressure cylinder, a high pressure cylinder, an intermediate pressure cylinder and a low pressure cylinder; the steam outlet of the ultrahigh pressure cylinder is respectively connected with the hybrid drive turbine and the high pressure heater, the hybrid drive turbine is provided with a steam extraction port, and the steam extraction port is connected with the high pressure heater; and the steam exhaust port of the intermediate pressure cylinder is respectively connected with the low pressure cylinder and the bypass turbine, and the steam exhaust port of the bypass turbine is connected with the condenser. The thermodynamic system greatly improves the economy of the generator set by the cascade utilization of energy; meanwhile, when the load of the generator set changes, the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder of the main machine are ensured to work within a working condition range with higher efficiency, the plant power consumption rate is reduced, and the overall working performance of secondary reheating is improved.
Description
Technical Field
The invention relates to the field of thermal power generation, in particular to a thermal system with double reheating.
Background
The intermediate reheating is that the steam expanded and done in the high pressure cylinder of the turbine is sent to the reheater of the boiler to be reheated to make the temperature reach or approach the temperature of the main steam, and then the reheated steam is sent back to the middle and low pressure cylinders of the turbine to continue to expand and do work. The reheating technology can increase the work of the steamAnd the enthalpy drop reduces the humidity of the steam expansion end, so that the working capacity of the steam and the generating efficiency of the unit are improved. The intermediate reheating can be divided into primary reheating and secondary reheating, and under the same steam pressure temperature parameter, the heat efficiency of the secondary reheating is improved by 2 percent compared with that of a primary reheating unit, and the heat efficiency of the secondary reheating is corresponding to CO2The emission reduction is about 3.6 percent. The operation performance of a plurality of ultra-supercritical secondary reheating units is provided abroad, representative power plants in Japan, Sichuan power plants and Nordjyland power plants in Denmark prove the technical economy and reliability of the secondary reheating technology. However, after the secondary reheating is adopted, the temperature difference between the regenerative steam extraction and the corresponding heat regenerator water supply is too large due to the fact that the degree of superheat of steam is greatly improved, and a large amount of fire loss is caused. The heat exchange temperature difference can be reduced by using an external steam cooler, but the function is very limited. Therefore, various solutions are tried by related enterprises and research teams at home and abroad, wherein the BESD turbine scheme of Shanghai electric power has certain application prospects in theory. According to the turbine scheme, a part of steam is separated from the exhaust steam of the ultrahigh pressure cylinder, enters a BESD turbine with special design to do work through expansion, and is used for driving a water feeding pump, and redundant power is merged into auxiliary power. The deaerator and part of high-pressure steam and low-pressure steam are directly extracted from the BESD turbine or exhaust steam of the BESD turbine is utilized; because the steam in the BESD turbine is not reheated, the problem of the superheat degree of extracted steam of a secondary reheating unit is avoided. The biggest problem of the scheme is the application of the power generation capacity of the BESD turbine, because the turbine runs at a fixed frequency, the efficiency is very low under variable working conditions, and a high-power frequency converter is needed when the generated electric energy is used for driving a water feeding pump, so that the equipment investment is large, and further energy loss is caused. In addition, because the pressure at the steam extraction point of the deaerator can not be kept constant under variable working conditions, the requirements of the deaerator are met by throttling, and the fire loss is very large.
Besides the above problems, when the high-power steam turbine operates under a high-load working condition, the problem of insufficient expansion of the last stage of the low-pressure cylinder still exists, and the economical efficiency of the unit is seriously affected. This is because, limited by the strength of the blade material, it is difficult for the turbine last stage flow area to reach an optimum value at high load, resulting in a decrease in low cylinder efficiency with an increase in load, and a further decrease in exhaust back pressure is limited. The problem of insufficient flow area of the final stage can be solved by adding a set of low-pressure cylinders, but the cost is too high, and the working reliability is reduced due to too complex rotor shaft system. However, as the load increases, the efficiency of the high and medium pressure cylinders increases, contrary to the trend of the low pressure cylinders.
Therefore, it is necessary to find an efficient thermal system for secondary reheating.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a double reheating thermal system, which greatly improves the economy of a generator set by using the energy in a gradient way; meanwhile, when the load of the generator set changes, the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder of the main machine are ensured to work within a working condition range with higher efficiency, the plant power consumption rate is reduced, and the overall working performance of secondary reheating is improved.
In order to achieve the above object, the present invention provides a thermal system for double reheating, which comprises a steam turbine, a condenser, a bypass turbine, a hybrid drive turbine and a high-pressure heater; the steam turbine comprises an ultrahigh pressure cylinder, a high pressure cylinder, an intermediate pressure cylinder and a low pressure cylinder; the steam outlet of the ultrahigh pressure cylinder is respectively connected with the hybrid drive turbine and the high pressure heater, the hybrid drive turbine is provided with a steam extraction port, and the steam extraction port is connected with the high pressure heater; and the steam exhaust port of the intermediate pressure cylinder is respectively connected with the low pressure cylinder and the bypass turbine, and the steam exhaust port of the bypass turbine is connected with the condenser.
Through the technical scheme of the invention, the following beneficial effects can be obtained:
(1) the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder of the main machine are operated in the high-efficiency area by controlling the steam extraction amount of the bypass turbine, so that the energy conversion efficiency of the main machine of the steam turbine is improved;
(2) the bypass turbine is provided with the auxiliary condenser independently, so that the back pressure of the main condenser can be reduced, the work-doing capacity of a main machine (a turbine) is improved, and the circulation efficiency of a unit is improved;
(3) the auxiliary generator matched with the bypass turbine generates power and is merged into a service power system, so that the service power rate is reduced;
(4) the bypass turbine has a frequency modulation function, and the power of the main machine is rapidly adjusted by adjusting the steam inlet quantity of the bypass turbine, so that the bypass turbine has a rapid frequency modulation function;
(5) exhaust steam of the hybrid drive turbine returns to the regenerative system and does not enter the condenser, so that the latent heat of vaporization of the part of steam is effectively utilized, and the loss of a cold source is reduced;
(6) the regenerative extracted steam of the hybrid drive turbine part is not reheated, the superheat degree is reduced, the loss is reduced, the reheated steam is mainly used for the large engine to do work, and the heat utilization is more effective;
(7) the superheat degree of extracted steam of the hybrid drive turbine part is reduced, the material grade of related extracted steam pipelines, valves and heaters is reduced, and the manufacturing cost of the pipelines, the valves and equipment is saved;
(8) the hybrid drive turbine design point is selected at a partial load (generally 70-85% THA working condition), namely the most frequently-operated working condition of the unit, so that the economical efficiency of the actual operation of the unit is greatly improved;
(9) the thermodynamic system provided by the invention enables the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder of the steam turbine to operate in the high-efficiency area by controlling the operation modes of the bypass turbine and the hybrid drive turbine, thereby greatly realizing the cascade utilization of the energy of the generator set and greatly improving the economy of the generator set.
Drawings
FIG. 1 is a schematic diagram of a two reheat thermodynamic system provided by the present invention.
Description of the reference numerals
1 ultrahigh pressure cylinder and 2 high pressure cylinders
3 middle pressure cylinder and 4 low pressure cylinders
5 main generator 6 condenser
7-bypass turbine 8 auxiliary generator
9 hybrid drive turbine 10 variable frequency engine
11 feed pump 12 high pressure heater
No. 13 oxygen-eliminating device 121 first high-pressure heater
No. 122 high pressure feed water heater No. 123 high pressure feed water heater No. three
Steam inlet of 124-IV high-pressure heater P1 ultrahigh-pressure cylinder
Steam exhaust port of P2 ultrahigh pressure cylinder P3 intermediate pressure cylinder
Steam inlet of P4 low pressure cylinder P5 bypass steam inlet of turbine
Exhaust port of P6 low pressure cylinder P7 bypass exhaust port of turbine
Condensate outlet of P8 main condenser P9 auxiliary condenser
Exhaust port P11 first extraction port of P10 hybrid drive turbine
P12 second extraction port P13 third extraction port
S1 first regulating valve S2 second regulating valve
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
As shown in fig. 1, the present invention provides a thermal system of double reheating, which includes a steam turbine, a condenser 6, a bypass turbine 7, a hybrid drive turbine 9, and a high-pressure heater 12; the steam turbine comprises an ultrahigh pressure cylinder 1, a high pressure cylinder 2, an intermediate pressure cylinder 3 and a low pressure cylinder 4; a steam outlet P2 of the ultra-high pressure cylinder 1 is respectively connected with the hybrid drive turbine 9 and the high pressure heater 12, a steam extraction port is arranged on the hybrid drive turbine 9, and the steam extraction port is connected with the high pressure heater 12; the exhaust port P3 of the intermediate pressure cylinder 3 is connected to the low pressure cylinder 4 and the bypass turbine 7, respectively, and the exhaust port P7 of the bypass turbine 7 is connected to the condenser 6.
In the present invention, the thermodynamic system further includes a boiler and a main generator 5, the boiler, the steam turbine and the main generator 5 are connected in sequence, preferably, the boiler is connected to the ultra-high pressure cylinder 1, and the power of the low pressure cylinder 4 is output to the main generator 5.
According to the difference of internal pressure grades and the sequence of steam admission, the steam turbine comprises an ultrahigh pressure cylinder 1, a high pressure cylinder 2, an intermediate pressure cylinder 3 and a low pressure cylinder 4 which are connected in sequence; preferably, the ultra high pressure cylinder 1, the high pressure cylinder 2, the intermediate pressure cylinder 3, and the low pressure cylinder 4 are sequentially connected by a single shaft.
According to the invention, the condensed water discharged from the condensed water outlet of the condenser 6 passes through the deaerator 13 and then is delivered to the high-pressure heater 12 through the water feed pump 11, preferably, the condensed water outlet of the condenser 6 is connected with the deaerator 13 through a pipeline, and the condensed water is delivered to the deaerator 13 through a pipeline and then delivered to the high-pressure heater 12 through the water feed pump 11.
According to the invention, the exhaust port P10 of the hybrid drive turbine 9 is connected to the deaerator 13; preferably, the exhaust steam generated by the hybrid drive turbine 9 during operation is piped via the steam outlet P10 to the deaerator 13.
In the present invention, the pressure at the exhaust port P10 of the hybrid drive turbine 9 is equal to or higher than the pressure of the deaerator 13; preferably, the pressure at the exhaust port P10 of the hybrid drive turbine 9 is not variable with operating conditions.
According to the invention, the power output by the hybrid drive turbine 9 can be used to power the feed pump 11. Preferably, the power output by the hybrid drive turbine 9 is less than or equal to the power of the feed water pump 11; more preferably, the hybrid drive turbine 9 is connected to a variable frequency motor 10 to jointly power the feed pump 11. Further preferably, the power output by the hybrid drive turbine 9 is smaller than the power of the feed water pump 11, and in operation, the part of the feed water pump 11 with insufficient power is driven by the variable frequency motor 10.
According to the invention, the thermodynamic system comprises at least one high-pressure heater 12, preferably 4-6 high-pressure heaters 12, and the high-pressure heaters 12 are connected in series. Preferably, the high-pressure heater 12 is connected to the steam extraction of the hybrid drive turbine 9. More preferably, the number of the steam extraction ports on the hybrid drive turbine 9 is less than or equal to the number of the high-pressure heaters 12. It is further preferred that at least one extraction opening, preferably 4 to 6 extraction openings, is provided on the hybrid drive turbine 9. Still further preferably, each steam extraction port corresponds to the high pressure heater 12.
In a preferred embodiment of the present invention, as shown in fig. 1, the thermodynamic system includes 4 high-pressure heaters 12 connected in sequence, which are a first high-pressure heater 121, a second high-pressure heater 122, a third high-pressure heater 123 and a fourth high-pressure heater 124, the fourth high-pressure heater 124 is connected to the feed water pump 11, condensed water generated by the condenser 6 is deaerated by the deaerator 13, then is input to the fourth high-pressure heater 124 through the feed water pump 11, and then passes through the third high-pressure heater 123, the second high-pressure heater 122 and the first high-pressure heater 121 in sequence, and feed water discharged by the first high-pressure heater 121 is returned to the boiler for recycling. More preferably, the hybrid drive turbine is provided with 3 steam extraction ports, which are respectively a steam extraction port P11, a steam extraction port P12 and a steam extraction port P13, and they are respectively connected with the second high-pressure heater 122, the third high-pressure heater 123 and the fourth high-pressure heater 124, so that the steam of the hybrid drive turbine 9 is respectively delivered to the respectively connected high-pressure heaters through the respective steam extraction ports, thereby achieving the purpose of supplying heat. Further preferably, the first high pressure heater 121 is connected to a steam outlet P2 of the ultra high pressure cylinder 1 to supply heat using steam generated by the ultra high pressure cylinder 1, and particularly, when the steam extraction amounts of the second high pressure heater 122, the third high pressure heater 123 and the fourth high pressure heater 124 are insufficient, the first high pressure heater 121 may supplement the heat supply.
According to the invention, the power of the bypass turbine 7 is output to an auxiliary generator 8; preferably, the auxiliary generator 8) is connected to an auxiliary distribution device and is used to supply power to the auxiliary distribution device; more preferably, the auxiliary power distribution equipment includes at least one of a variable frequency motor 10, a condensate pump, a fan (including a blower, an induced draft fan, a primary fan, etc.), a vacuum pump, and an environmental protection device.
According to the present invention, the condenser 6 preferably includes a main condenser 61 and an auxiliary condenser 62, the main condenser 61 is connected to a steam discharge port P6 of the low pressure cylinder 4, and the auxiliary condenser 62 is connected to a steam discharge port of the bypass turbine 7. More preferably, the condensed water outlet P8 of the main condenser 61 and the condensed water outlet P9 of the auxiliary condenser 62 are connected to the same condensed water pipe, and the condensed water pipe is connected to the deaerator 13.
According to the invention, a first regulating valve S1 is provided between the exhaust port P3 of the intermediate pressure cylinder 3 and the intake port P5 of the bypass turbine 7, and the first regulating valve S1 is used for regulating the intake pressure of the bypass turbine 7.
In a preferred embodiment of the present invention, when the load of the plant changes, the first regulating valve S1 is used to adjust the steam inlet amount of the bypass turbine 7 to maintain the operation of the ultra high pressure cylinder 1, the high pressure cylinder 2, the intermediate pressure cylinder 3 and the low pressure cylinder 4 of the steam turbine in a high efficiency range; in addition, the power of the turbine can be rapidly adjusted by adjusting the steam inlet amount of the bypass turbine through the first adjusting valve S1, so that a function of rapid frequency modulation is provided.
According to the invention, a second regulating valve S2 is arranged between the steam outlet P2 of the ultra-high pressure cylinder 1 and the steam inlet of the hybrid drive turbine 9, and the second regulating valve S2 is used for regulating the steam inlet pressure of the hybrid drive turbine 9.
In a preferred embodiment of the present invention, when the load of the unit is reduced, the steam inlet pressure of the hybrid driving turbine 9, the power consumption and the rotation speed of the feed water pump 11 are all reduced along with the reduction of the load, the pressure drop, the enthalpy drop and the steam extraction amount of each high pressure heater 12 of each stage are also reduced along with the reduction of the rotation speed and the total pressure drop, and the steam outlet pressure of the hybrid driving turbine 9 can be maintained constant only by slightly adjusting the second adjusting valve S2; during operation, the power consumption of the feed pump 11 and the back pressure of the hybrid drive turbine 9 are preferably met.
According to the invention, the bypass turbine 7 is preferably a pure condensing turbine; more preferably, the hybrid drive turbine 9 is a back-extraction turbine.
The invention also provides a control method of the thermodynamic system, which comprises the following steps:
(1) under low load conditions (for example, generally lower than 70% of rated load), the bypass turbine is closed through the first regulating valve S1 to ensure that the steam flow of the low pressure cylinder 4 under the working condition is closer to the steam flow under the optimal working condition; the economic working condition of the hybrid drive turbine 9 is the water feeding pump power corresponding to the annual average working condition of the steam turbine, and the hybrid drive turbine 9 can directly drive the water feeding pump 11 under the low-load working condition, so that the service current is reduced;
(2) under a high load condition (for example, generally higher than 75% of rated load), the steam inlet amount of the bypass turbine 7 is controlled by adjusting the first adjusting valve S1, so that the ultra-high pressure cylinder 1, the high pressure cylinder 2, the intermediate pressure cylinder 3 and the low pressure cylinder 4 of the steam turbine are all in a high-efficiency area; and starting the variable frequency motor 10, and driving a feed water pump to operate together with the hybrid drive turbine 9 so as to maintain the power of the hybrid drive turbine 9 unchanged during the variation of the unit load working condition.
In the present invention, the term "low load condition" generally refers to less than 70% of rated load, but may be appropriately adjusted according to the optimum operating point of various turbine models.
In the present invention, the term "high load condition" generally refers to a load higher than 75% of the rated load, but may be appropriately adjusted according to the optimum operating point of various turbine models.
Preferably, the bypass turbine 7 adjusts the steam inlet amount while the power of the steam turbine is maintained, thereby indirectly changing the steam inlet amounts of the ultrahigh pressure cylinder 1, the high pressure cylinder 2, the intermediate pressure cylinder 3 and the low pressure cylinder 4 of the steam turbine. For example, combining a certain subcritical 600MW turbine performance characteristic curve provided by the manufacturer, the thermal balance calculation yields: under the high-load working condition, along with the increase of the steam inlet amount of the bypass turbine 7, the steam inlet amounts of the high-pressure cylinder 2 and the intermediate-pressure cylinder 3 are in an increasing trend, and the steam inlet amount of the low-pressure cylinder 4 is in a decreasing trend, so that the efficiency of the high-pressure cylinder 2 of the steam turbine is increased, the efficiency of the intermediate-pressure cylinder 3 is basically unchanged, and the efficiency of the low-pressure cylinder 4 is increased, so that the phenomenon that the low-pressure cylinder is not expanded enough due to overlarge flow is effectively avoided.
The present invention will be described in detail below by way of examples.
Example 1
The arrangement of the thermal system of the double reheating provided by the invention is shown as the attached figure 1. The thermodynamic system mainly comprises a condenser 6 (preferably comprising a main condenser 61 and an auxiliary condenser 62), a bypass turbine 7, a hybrid drive turbine 9, 4 high-pressure heaters (a first high-pressure heater 121, a second high-pressure heater 122, a third high-pressure heater 123 and a fourth high-pressure heater 124 respectively), a boiler, a steam turbine (comprising an ultrahigh pressure cylinder 1, a high pressure cylinder 2, an intermediate pressure cylinder 3 and a low pressure cylinder 4 which are connected in sequence), and a main generator 5, wherein steam generated by the boiler enters the ultrahigh pressure cylinder 1 through a steam inlet P1 of the ultrahigh pressure cylinder 1, power generated by the low pressure cylinder 4 is output to the main generator 5 to be used for supplying power to various power distribution equipment (such as a steam turbine and the like), steam discharged from the low pressure cylinder 4 is discharged through a steam outlet P6 of the low pressure cylinder and then is conveyed to the main condenser 61 to form condensed water which is conveyed to a deaerator 13 through a pipeline, the water is pumped into a fourth high-pressure heater 124 through a water feeding pump 11, and then the water is heated by a third high-pressure heater, a second high-pressure heater and a first high-pressure heater in sequence and then returns to the regenerative system.
The exhaust steam of the intermediate pressure cylinder 3 of the steam turbine is discharged through an exhaust steam port P3 of the intermediate pressure cylinder, then enters the low pressure cylinder 4 through a steam inlet P4 of the low pressure cylinder and enters the bypass turbine 7 through a steam inlet P5 of the bypass turbine, the exhaust steam port P7 of the bypass turbine 7 is connected with the auxiliary condenser 6, the condensed water generated by the auxiliary condenser 6 is discharged through a condensed water outlet P9 of the auxiliary condenser, and then is input into the deaerator 13 together with the condensed water discharged through a condensed water outlet P8 of the main condenser. And, the power generated by the bypass turbine 7 is output to the auxiliary generator 8 for power supply of each power distribution equipment (such as the inverter motor 10 and the like).
The ultrahigh pressure cylinder 1 of the steam turbine enters the first high pressure heater 121, part of exhausted steam enters the hybrid drive turbine 9, enters the hybrid drive turbine 9 through the second regulating valve S2 to expand and do work, and exhausted steam directly enters the deaerator 13 through the steam exhaust port P10. The hybrid drive turbine 9 is provided with 3 non-adjustable steam extraction ports for supplying steam to a second high-pressure heater, a third high-pressure heater and a fourth high-pressure heater respectively; the hybrid drive turbine 9 directly drives the feed pump 11, and the variable-speed operation is required according to the performance of the feed pump 11. The economic working condition of the hybrid driving turbine 9 is the power of a water feeding pump corresponding to the annual average working condition of a main machine (a steam turbine), moreover, the power of the hybrid driving turbine 9 does not exceed the power consumption of the water feeding pump under any working condition, and the part with insufficient power is driven by the variable frequency motor 10 during operation. The exhaust pressure of the hybrid drive turbine 9 is equal to or slightly higher than the pressure of the deaerator 13 and does not vary with the operating conditions.
Under a high load condition (higher than 75% of rated load), the steam inlet quantity of the bypass turbine 7 is controlled by adjusting the first adjusting valve S1, so that the ultrahigh pressure cylinder 1, the high pressure cylinder 2, the intermediate pressure cylinder 3 and the low pressure cylinder 4 of the steam turbine are all in a high-efficiency area; and starting the variable frequency motor 10, and driving a feed water pump to operate together with the hybrid drive turbine 9 so as to maintain the power of the hybrid drive turbine 9 unchanged during the variation of the unit load working condition.
Under the condition of low load (lower than 70% of rated load), the bypass turbine is closed through the first regulating valve S1 to ensure that the steam flow of the low pressure cylinder 4 under the working condition is closer to the steam flow under the optimal working condition; the economic working condition of the hybrid drive turbine 9 is the water feeding pump power corresponding to the annual average working condition of the steam turbine, and the hybrid drive turbine 9 can directly drive the water feeding pump 11 under the low-load working condition, so that the service current is reduced.
The thermal system for double reheating mainly comprises a steam turbine, a bypass turbine and a hybrid drive turbine, and through reasonable matching and operation optimization among the steam turbine, the bypass turbine and the hybrid drive turbine, high-pressure cylinders, medium-pressure cylinders and low-pressure cylinders of the steam turbine under different working conditions are all in a high-efficiency area, gradient utilization of energy is achieved to the maximum extent, and economical efficiency of a generator set is greatly improved.
Compared to conventional double reheat technology (i.e. thermodynamic system without the introduction of bypass turbine 7, auxiliary condenser 62, hybrid drive turbine 9 and variable frequency motor 10):
1) the efficiency of the hybrid drive turbine 9 is improved by more than 5 percent compared with that of a conventional small water feeding pump turbine;
2) the relative internal efficiency of the high-pressure cylinder is increased by about 0.6 percent, and the relative internal efficiency of the low-pressure cylinder is increased by about 0.3 percent;
3) the heat load of the main condenser is reduced, and the back pressure of a main machine (a steam turbine) is reduced by about 0.3 kPa;
4) the heat consumption of the unit is reduced by about 68.2kJ/kWh, and the coal consumption is reduced by more than 2.6 g/kWh;
5) the plant power consumption of the unit is reduced by about 4-5%.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (21)
1. A thermal system for double reheating is characterized by comprising a steam turbine, a condenser (6), a bypass turbine (7), a hybrid drive turbine (9) and a high-pressure heater (12); the steam turbine comprises an ultrahigh pressure cylinder (1), a high pressure cylinder (2), an intermediate pressure cylinder (3) and a low pressure cylinder (4); a steam outlet (P2) of the ultra-high pressure cylinder (1) is respectively connected with the hybrid drive turbine (9) and the high pressure heater (12), a steam extraction port is arranged on the hybrid drive turbine (9), and the steam extraction port is connected with the high pressure heater (12); the steam exhaust port (P3) of the intermediate pressure cylinder (3) is respectively connected with the low pressure cylinder (4) and the bypass turbine (7), and the steam exhaust port (P7) of the bypass turbine (7) is connected with the condenser (6).
2. A thermodynamic system as claimed in claim 1, wherein the condensed water discharged from the condensed water outlet of the condenser (6) is passed through a deaerator (13) and then delivered to the high-pressure heater (12) by a feed water pump (11).
3. A thermodynamic system as claimed in claim 2, wherein the exhaust port (P10) of the hybrid drive turbine (9) is connected to the deaerator (13).
4. A thermodynamic system as claimed in claim 3, wherein the pressure at the exhaust port (P10) of the hybrid drive turbine (9) is greater than or equal to the pressure of the deaerator (13).
5. A thermodynamic system as claimed in claim 2, wherein the power output by the hybrid drive turbine (9) is used to power the feedwater pump (11).
6. A thermodynamic system as claimed in claim 5, wherein the power output by the hybrid drive turbine (9) is less than or equal to the power of the feedwater pump (11).
7. A thermodynamic system as claimed in claim 6, wherein the hybrid drive turbine (9) is connected to a variable frequency motor (10) to jointly power the feedwater pump (11).
8. A thermodynamic system as claimed in any one of claims 1 to 7, wherein the thermodynamic system includes at least one high pressure heater (12).
9. A thermodynamic system as claimed in claim 8, wherein the thermodynamic system comprises 4-6 high pressure heaters (12).
10. Thermodynamic system according to any one of claims 1-7, wherein at least one steam extraction is provided on the hybrid drive turbine (9).
11. A thermodynamic system as claimed in claim 10, wherein 4-6 extraction ports are provided on the hybrid drive turbine (9).
12. A thermodynamic system as claimed in claim 11, wherein the steam extraction ports correspond to the high pressure heaters (12), respectively.
13. A thermodynamic system as claimed in any one of claims 1 to 7, wherein the power of the bypass turbine (7) is output to an auxiliary generator (8).
14. A thermodynamic system as claimed in claim 13, wherein the auxiliary generator (8) is connected to an auxiliary power distribution device and is used to power the auxiliary power distribution device.
15. A thermodynamic system as claimed in claim 14, wherein the auxiliary power distribution equipment comprises at least one of a variable frequency motor (10), a condensate pump, a fan, a vacuum pump and an environmental protection device.
16. A thermodynamic system according to any one of claims 2-7, wherein the condenser (6) comprises a main condenser (61) and an auxiliary condenser (62), the exhaust port (P6) of the low pressure cylinder (4) being connected to the main condenser (61), and the exhaust port of the bypass turbine (7) being connected to the auxiliary condenser (62).
17. A thermodynamic system according to claim 16, wherein the condensed water outlet (P8) of the main condenser (61) and the condensed water outlet (P9) of the auxiliary condenser (62) are connected to the same condensed water conduit, which is connected to the oxygen scavenger (13).
18. Thermodynamic system according to any one of claims 1-7, wherein a first regulating valve (S1) is provided between the exhaust port (P3) of the intermediate pressure cylinder (3) and the inlet port (P5) of the bypass turbine (7).
19. A thermodynamic system as claimed in any one of claims 1 to 7, wherein a second regulating valve (S2) is provided between the exhaust (P2) of the ultra high pressure cylinder (1) and the inlet of the hybrid drive turbine (9).
20. A thermodynamic system as claimed in any one of claims 1 to 7, wherein the bypass turbine (7) is a pure condensing turbine.
21. A thermodynamic system as claimed in any one of claims 1 to 7, wherein the hybrid drive turbine (9) is a back-extraction turbine.
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| CN109404070A (en) * | 2018-10-30 | 2019-03-01 | 中国华能集团清洁能源技术研究院有限公司 | A kind of the pass-out steam turbine power generator and method cooling using deep sea water |
| CN109296413B (en) * | 2018-10-30 | 2024-01-30 | 中国华能集团清洁能源技术研究院有限公司 | Bypass secondary reheating power generation device and method cooled by deep seawater |
| CN110735674A (en) * | 2019-10-31 | 2020-01-31 | 大唐郓城发电有限公司 | Operation-controllable double-machine regenerative system |
| CN113006891A (en) * | 2021-02-26 | 2021-06-22 | 西安热工研究院有限公司 | Comprehensive frequency modulation system and method for coupling heat supply and low-pressure steam extraction |
| CN114856733A (en) * | 2022-05-18 | 2022-08-05 | 西安热工研究院有限公司 | Steam turbine set power generation system |
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