CN117167105A - Supercritical carbon dioxide cyclic power generation peak regulation system and peak regulation method - Google Patents
Supercritical carbon dioxide cyclic power generation peak regulation system and peak regulation method Download PDFInfo
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- CURLTUGMZLYLDI-UHFFFAOYSA-N carbon dioxide Natural products O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 title claims abstract description 97
- 238000010248 power generation Methods 0.000 title claims abstract description 71
- 229910002092 carbon dioxide Inorganic materials 0.000 title claims abstract description 50
- 239000001569 carbon dioxide Substances 0.000 title claims abstract description 50
- 238000000034 method Methods 0.000 title claims abstract description 23
- 230000033228 biological regulation Effects 0.000 title abstract description 42
- 230000001105 regulatory effect Effects 0.000 claims description 17
- 230000008878 coupling Effects 0.000 claims description 13
- 238000010168 coupling process Methods 0.000 claims description 13
- 238000005859 coupling reaction Methods 0.000 claims description 13
- 230000007423 decrease Effects 0.000 claims description 11
- 150000003839 salts Chemical class 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 4
- 230000008569 process Effects 0.000 claims description 4
- 230000005611 electricity Effects 0.000 claims description 3
- 230000008859 change Effects 0.000 abstract description 10
- 238000001816 cooling Methods 0.000 description 18
- 230000000052 comparative effect Effects 0.000 description 15
- 238000005457 optimization Methods 0.000 description 6
- 230000008901 benefit Effects 0.000 description 5
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- 230000009286 beneficial effect Effects 0.000 description 4
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- 238000010586 diagram Methods 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- 230000006872 improvement Effects 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000011217 control strategy Methods 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000005338 heat storage Methods 0.000 description 1
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Abstract
The invention belongs to the technical field related to advanced power cycle power generation, and discloses a supercritical carbon dioxide cycle power generation peak regulation system and a peak regulation method, wherein the turbomachinery equipment of the supercritical carbon dioxide cycle power generation peak regulation system mainly comprises a turbine, a compressor and a heat exchanger, wherein a main compressor or a recompression and the turbine are connected with a shaft and are driven by the turbine, and other compressors are connected with independent driving structures. According to the invention, the main compressor or the recompressor is arranged with the turbine connecting shaft, and the turbine can directly drive the compressor through the turbine and the compressor connecting shaft arrangement, so that the extra energy loss caused by driving the compressor by the motor is reduced, and the efficiency is improved; the other compressors are independently arranged in a split shaft mode, so that the shaft rotation speeds of the other compressors can be flexibly adjusted under peak load regulation, the change of the peak load regulation can be flexibly adapted, and the optimal operation parameters can be obtained under peak load regulation in an optimized mode, and therefore the power generation efficiency of the system is guaranteed not to be greatly reduced under a peak load regulation scene.
Description
Technical Field
The invention belongs to the technical field related to advanced power cycle power generation, and particularly relates to a supercritical carbon dioxide cycle power generation peak regulation system and a peak regulation method.
Background
The concentrated solar thermal power generation (Concentrated Solar Power, CSP for short) system provided with the heat storage device can realize flexible regulation and control of output power, can be used as a base load power station to provide stable power, is more hopeful to become a clean and reliable peak regulation power station for absorbing surplus photovoltaic power and wind power in a future high-proportion renewable energy system, and further facilitates large-scale grid connection of renewable energy power.
Among numerous CSP technologies, tower type solar thermal power generation technologies are combined with high-temperature heat absorption and storage devices and supercritical CO 2 (supercritical CO 2 Short for S-CO 2 ) The brayton cycle has great potential to further increase the power generation efficiency and reduce the power generation cost, and has received much attention in recent years. S-CO 2 The circulation is used as important heat-power conversion equipment of the CSP system, the operation characteristic of the heat-power conversion equipment has obvious influence on the operation performance of the CSP system, and S-CO 2 The optimization of the cycle design and the related research of the regulation and control of the operation parameters are very important.
Existing supercritical CO 2 The circulation system has great potential in terms of improving the power generation efficiency and reducing the power generation cost when being used for power generation, but can only ensure that the power generation efficiency is higher under rated load, and has the problem that the power generation efficiency is greatly reduced along with the change of peak shaving load when being used in peak shaving scenes. Therefore, in order to meet the urgent peak shaving demands of the future high-proportion renewable energy system, how to determine the optimal design scheme of the circulating equipment, so that the circulating operation is flexible, efficient and safe under the complex variable load working condition, and the method needs to be thoroughly studied.
Disclosure of Invention
In response to the above-mentioned shortcomings or improvements of the prior art, the present invention provides a supercritical carbon dioxide cycle power generationPeak regulating system and peak regulating method, solving the problem of existing supercritical CO 2 When the circulating system is used for peak shaving scenes, the problem that the power generation efficiency is greatly reduced along with the change of peak shaving load exists, the requirement of circulating flexible operation under partial load can be met, the circulating high-efficiency performance is considered, and the circulating system is suitable for peak shaving scenes.
In order to achieve the above object, according to one aspect of the present invention, there is provided a supercritical carbon dioxide cycle power generation peak shaving system, a turbomachinery apparatus of the supercritical carbon dioxide cycle power generation peak shaving system including a turbine, a precompressor, a main compressor and a recompressor, wherein the main compressor or the recompressor is arranged with the turbine coupling, driven by the turbine, and the remaining compressors are connected with independent driving structures.
According to the supercritical carbon dioxide circulating power generation peak shaving system provided by the invention, when the required peak shaving load is 30% -55% of rated load, the main compressor and the turbine are arranged in a connecting shaft way, and the precompressor and the recompressor are respectively connected with an independent driving structure;
when the required peak regulating load is 55% -100% of the rated load, the recompressor and the turbine are arranged in a connecting shaft way, and the precompressor and the main compressor are respectively connected with independent driving structures.
According to the supercritical carbon dioxide cycle power generation peak shaving system provided by the invention, the supercritical carbon dioxide cycle power generation peak shaving system further comprises: the device comprises a high-temperature heat regenerator, a low-temperature heat regenerator, a pre-cooler, a flow dividing valve, an intercooler and a heater;
the outlet of the turbine is connected with the first inlet of the high-temperature heat regenerator, the first outlet of the high-temperature heat regenerator is connected with the first inlet of the low-temperature heat regenerator, the second outlet of the high-temperature heat regenerator is connected with the inlet of the heater, the outlet of the heater is connected with the inlet of the turbine, the first outlet of the low-temperature heat regenerator is connected with the inlet of the pre-cooler, the outlet of the pre-cooler is connected with the inlet of the pre-compressor, the outlet of the pre-compressor is connected with the inlet of the intercooler and the inlet of the recompressor respectively through the shunt valve, the outlet of the intercooler is connected with the inlet of the main compressor, the outlet of the main compressor is connected with the second inlet of the low-temperature heat regenerator, the second outlet of the low-temperature heat regenerator is connected with the second inlet of the high-temperature heat regenerator, and the outlet of the recompression is connected with the second inlet of the high-temperature heat regenerator.
According to the supercritical carbon dioxide circulating power generation peak shaving system provided by the invention, the heating medium in the heater is molten salt; the split ratio of the split valve is 0.5-0.6.
According to the supercritical carbon dioxide circulating power generation peak shaving system provided by the invention, the temperature of an inlet medium of the turbine is more than or equal to 600 ℃; the inlet medium temperatures of the pre-compressor, the main compressor and the recompressor are each greater than 30.98 ℃.
According to another aspect of the present invention, there is provided a supercritical carbon dioxide cycle power generation peak shaving method, based on any one of the above supercritical carbon dioxide cycle power generation peak shaving systems, the method comprising:
the main compressor or the recompression is connected with the turbine through a shaft, the turbine is driven, and other compressors are connected with an independent driving structure and used for peak shaving of which the required peak shaving load is in the range of 30% -100% of rated load.
According to the supercritical carbon dioxide cycle power generation peak shaving method provided by the invention, when the required peak shaving load is 30% -55% of rated load, the main compressor and the turbine are arranged in a connecting shaft way, and the precompressor and the recompressor are respectively connected with an independent driving structure;
and when the required peak load is 55-100% of the rated load, arranging the recompressor and the turbine connecting shaft, and respectively connecting the precompressor and the main compressor with independent driving structures.
According to the supercritical carbon dioxide cycle power generation peak shaving method provided by the invention, when the arrangement scheme of the main compressor and the turbine connecting shaft is adopted, the shaft rotation speeds of the main compressor and the recompressor gradually decrease and the shaft rotation speed of the precompressor gradually increases along with the reduction of the required peak shaving load.
According to the supercritical carbon dioxide cycle power generation peak shaving method provided by the invention, when the arrangement scheme of the recompressor and the turbine connecting shaft is adopted, the shaft rotating speed of the recompression gradually decreases along with the decrease of the required peak shaving load, the shaft rotating speed of the main compressor is firstly decreased and then increased, and the shaft rotating speed of the precompressor gradually increases.
According to the supercritical carbon dioxide cycle power generation peak shaving method provided by the invention, the shunt ratio of the system is kept unchanged in the process of changing the required peak shaving load; wherein the split ratio is the ratio of the working medium flow of the main compressor to the total working medium flow of the main compressor and the recompressor.
In general, compared with the prior art, the supercritical carbon dioxide cycle power generation peak regulation system and the peak regulation method provided by the invention have the technical scheme that the invention is designed:
1. the main compressor or the recompressor is arranged with the turbine connecting shaft, other compressors are independently arranged in a split shaft mode, and the turbine can be directly driven by the turbine through the turbine and compressor connecting shaft arrangement, so that extra energy loss caused by driving the compressor by a motor is reduced, and efficiency is improved; the shaft rotation speeds of the other compressors can be flexibly adjusted by the independent split shaft arrangement, the shaft rotation speeds of the main compressor or the recompressor can also be adjusted by the turbine, and the three compressors can independently adjust the shaft rotation speeds along with the change of peak shaving load when the compressor is used in a peak shaving scene, so that the compressor can flexibly adapt to the change of peak shaving load, is beneficial to optimizing and acquiring optimal operation parameters under the peak shaving load, and further ensures that the power generation efficiency of the system is not greatly reduced under the peak shaving scene;
2. the system can meet the requirement of flexible circulation operation under partial load, and also has high efficiency performance of circulation, thus being applicable to peak shaving scenes;
3. the working characteristics of the three types of compressors under different loads are deeply considered, the working characteristics of the three types of compressors comprise the power consumption characteristics and the performance change characteristics along with the load change, and further, different circulation setting schemes are provided based on different peak shaving depth requirements, so that the maximum improvement of the circulating power generation efficiency under a peak shaving scene is facilitated.
Drawings
FIG. 1 is a schematic diagram of a supercritical carbon dioxide cycle power generation peak shaving system provided by the invention when a main compressor is arranged with a turbine coupling;
FIG. 2 is a schematic diagram of a supercritical carbon dioxide cycle power generation peak shaving system with a recompression and turbine coupling arrangement provided by the present invention;
FIG. 3 is a schematic diagram of the systems of comparative examples 1 and 2 provided by the present invention;
FIG. 4 is a schematic diagram of the systems of comparative example 3 and comparative example 4 provided by the present invention.
The same reference numbers are used throughout the drawings to reference like elements or structures, wherein:
1. a turbine; 2. a high temperature regenerator; 3. a low temperature regenerator; 4. a pre-cooler; 5. a precompressor; 6. a diverter valve; 7. an intercooler; 8. a main compressor; 9. a recompression machine; 10. a heater.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
Referring to fig. 1 and 2, the present invention provides a peak regulation system for supercritical carbon dioxide cycle power generation, which includes a supercritical carbon dioxide cycle system, and a turbomachinery of the supercritical carbon dioxide cycle system includes a turbine 1, a precompressor 5, a main compressor 8 and a recompressor 9, wherein the main compressor 8 or the recompressor 9 is arranged in a connecting shaft with the turbine 1, is driven by the turbine 1, and the other compressors are connected with independent driving structures.
The peak shaving system is formed by a supercritical carbon dioxide circulating system, wherein the supercritical carbon dioxide circulating system can be a Brayton circulating system and is a power generation system taking supercritical carbon dioxide as a working medium. The supercritical carbon dioxide circulation system, which generally comprises a compressor and a turbine 1, and other related structures for implementing a power generation cycle, is well known to those skilled in the art and will not be described in detail. In this embodiment three compressors are provided in the circulation system, namely a precompressor 5, a main compressor 8 and a recompressor 9.
Further, this embodiment proposes that the main compressor 8 or the recompression 9 is driven by the turbine 1 through the coupling arrangement of the main compressor and the turbine 1, and the other compressors are driven independently through the split shaft arrangement, so that the circulation system can be suitable for peak shaving. Specifically, first, the present embodiment considers the system composed of S-CO 2 According to the thermal performance analysis of the circulation, the total power consumption of the compressor can account for 25% -30% of the output power of the turbine 1, so that the compression power consumption is huge, the turbine 1 can be directly driven by the turbine 1 through the arrangement of the connecting shaft of the turbine 1 and the compressor, and the extra energy loss caused by driving the compressor by a motor is reduced, so that the efficiency is improved.
In addition, in the embodiment, the difference between the running pressure ratio of the compressors in the circulation system and the flow rate of the working medium flowing through the compressors is obvious, the rotation speeds of the compressors are different, and the compressors are required to be regulated and controlled relatively independently under the variable working condition, namely, the rotation speeds of the shafts of the compressors are required to be regulated and controlled under the variable load peak regulation running scene, so that the pressure ratio and the flow rate of the compressors are required to be regulated and controlled. Thus, in this embodiment, one compressor is selected to be coupled to the turbine 1, while the other compressors are independently driven and may be separately driven by a motor.
In particular, for the arrangement of the turbine 1 and the main compressor 8, the shaft speed of the turbine 1 is consistent with the shaft speed of the main compressor 8, and the shaft speeds of the precompressor 5 and the recompressor 9 can be flexibly adjusted; for the coupling arrangement of the turbine 1 and the recompressor 9, the shaft speed of the turbine 1 is identical to the shaft speed of the recompressor 9, while the shaft speeds of the precompressor 5 and the main compressor 8 can be flexibly adjusted. Therefore, the scheme of the embodiment not only can meet the requirement of flexible operation of circulation under partial load, but also gives consideration to the high-efficiency performance of circulation.
According to the supercritical carbon dioxide circulating power generation peak regulation system provided by the invention, the main compressor 8 or the recompressor 9 is arranged in a connecting shaft way with the turbine 1, other compressors are independently arranged in a split shaft way, and the turbine 1 can directly drive the compressor through the connecting shaft arrangement of the turbine 1 and the compressor, so that the extra energy loss caused by driving the compressor by a motor is reduced, and the efficiency is improved; the shaft rotation speeds of the other compressors can be flexibly adjusted by the independent split shaft arrangement, the shaft rotation speeds of the main compressor or the recompressor can also be adjusted by the turbine, and the three compressors can independently adjust the shaft rotation speeds along with the change of peak shaving load when the compressor is used in a peak shaving scene, so that the compressor can flexibly adapt to the change of peak shaving load, is beneficial to optimizing and acquiring optimal operation parameters under the peak shaving load, and further ensures that the power generation efficiency of the system is not greatly reduced under the peak shaving scene; the system can meet the requirement of flexible circulation operation under partial load, and also has high efficiency performance of circulation, thus being suitable for peak shaving scenes.
Further, researches show that the supercritical carbon dioxide circulating power generation peak shaving system can be used for peak shaving with peak shaving load within the range of 30% -100% of rated load by selecting the main compressor 8 or the recompression 9 to be arranged in a connecting shaft with the turbine 1 and other compressors to be independently driven, and can realize efficient and flexible operation of circulation with installed capacity of tens to hundreds of MW under the load demand of 30% -100%.
The supercritical carbon dioxide cycle power generation peak shaving system selected in the embodiment is provided with three compressors, namely a precompressor, a main compressor and a recompression compressor, and an intermediate cooling process is introduced on the basis of the recompression cycle through the introduction of the precompressor, so that a partial cooling cycle is formed. The cycle may further reduce compressor power consumption compared to a recompression cycle, thereby improving cycle efficiency.
Further, when the required peak load is 30% -55% of rated load, the main compressor 8 and the turbine 1 are arranged in a connecting shaft way, and the precompressor 5 and the recompressor 9 are respectively connected with independent driving structures; when the required peak load is 55% -100% of the rated load, the recompressor 9 is connected with the turbine 1 in a shaft way, and the precompressor 5 and the main compressor 8 are respectively connected with independent driving structures.
In the embodiment, the fact that the power consumption of the recompressor is remarkably highest in three types of compressors under high load is considered, and the arrangement of the recompressor and the turbine connecting shaft can reduce the extra power consumption caused by driving the compressor by the motor to the greatest extent, so that the thermal efficiency of the arrangement scheme is higher under high load; with the reduction of load, the performance attenuation of the main compressor is most obvious in three types of compressors, the cycle of the arrangement of the main compressor and the turbine connecting shaft has the minimum change of the pressure ratio of the main compressor under partial load, so that the cycle efficiency of the main compressor is higher, and the functional power attenuation of the turbine is also minimum, so that the thermal efficiency of the arrangement of the main compressor and the turbine connecting shaft is higher when the deep load is adjusted.
According to different peak regulation depth requirements, two mechanical arrangement forms of the turbine 1 exist, so that the supercritical carbon dioxide circulation system shows higher operation efficiency in different load-changing intervals, one is that when peak regulation load is mostly 30% -55% of rated power of circulation, the main compressor 8 and the turbine 1 are arranged in a connecting way, and when peak regulation load is mostly 55% -100% of rated power of circulation, the recompression 9 and the turbine 1 are arranged in a connecting way, mechanical power consumed by the compressor arranged with the turbine 1 in a connecting way is provided by the turbine 1, and other compressors are driven by independent motors.
Specifically, the turbine 1 and main compressor 8 or turbine 1 and recompressor 9 may be arranged in tandem according to actual peak shaving requirements. When the actual peak regulation load is distributed in 30% -55% of the rated load, a scheme of connecting the main compressor 8 with the turbine 1 is adopted; when the actual peak regulation load is distributed in 55% -100% of the rated load, a scheme of connecting the recompression 9 and the turbine 1 is adopted. The specific actual peak regulation load required can be judged according to the actual running load of a user in one year, and when the actual running load of the user in one year is mostly concentrated at 30% -55% of the rated load, a scheme of connecting the main compressor 8 and the turbine 1 can be adopted for the user; when the actual operating load of the user is mostly concentrated in 55% -100% of the rated load in one year, a scheme of coupling the recompression 9 with the turbine 1 can be adopted for the user.
Further, the invention specifically selects the supercritical CO 2 Part of the cooling cycle is the research object, and the supercritical carbon dioxide circulating system further comprises: a high temperature heat regenerator 2, a low temperature heat regenerator 3, a pre-cooler 4, a diverter valve 6, an intercooler 7 and a heater 10; namely, the main compressor 8 or the recompression 9 in the partial cooling circulation is connected with the turbine 1 in a shaft way, and the rest compressors are arranged in an independent split shaft way; supercritical CO 2 The partial cooling cycle includes: turbine 1, high temperature regenerator 2, low temperature regenerator 3, pre-cooler 4, pre-compressor 5, diverter valve 6, intercooler 7, main compressor 8, recompressor 9, heater 10. In which the main compressor 8 or the recompressor 9 is arranged in conjunction with the turbine 1, the mechanical work consumed being provided by the turbine 1 and the remaining compressors being driven by separate motors.
Specifically, the outlet of the turbine 1 is connected to the first inlet of the high-temperature regenerator 2, the first outlet of the high-temperature regenerator 2 is connected to the first inlet of the low-temperature regenerator 3, the second outlet of the high-temperature regenerator 2 is connected to the inlet of the heater 10, the outlet of the heater 10 is connected to the inlet of the turbine 1, the first outlet of the low-temperature regenerator 3 is connected to the inlet of the precompressor 5, the outlet of the precompressor 5 is connected to the inlet of the main compressor 8 and the inlet of the recompressor 9 through the shunt valve 6, the outlet of the main compressor 8 is connected to the second inlet of the low-temperature regenerator 3, the second outlet of the low-temperature regenerator 3 is connected to the second inlet of the high-temperature regenerator 2, the outlet of the recompressor 9 is connected to the second inlet of the high-temperature regenerator 2, the inlet of the precompressor 5 is provided with the precompressor 4, and the inlet of the main compressor 8 is provided with the intercooler 7.
Further, the heating medium in the heater 10 is molten salt; molten salt may be formed by solar heating. The split ratio of the split valve 6 is 0.5-0.6; the split ratio of the splitter valve 6 is the ratio of the flow of the working medium flowing into the main compressor 8 by the splitter valve 6 to the total flow of the working medium at the inlet of the splitter valve 6, and researches show that the split ratio in the range can obtain better power generation efficiency under different peak load.
Further, the inlet medium temperature of the turbine 1 is greater than or equal to 600 ℃; the inlet medium temperatures of the precompressor 5, the main compressor 8 and the recompressor 9 are each greater than 30.98 ℃. When the inlet temperature of the turbine 1 is higher than 600 ℃, supercritical CO is obtained 2 The cycle has a thermal efficiency advantage over conventional steam rankine cycles, and the more significant the thermal efficiency advantage as the temperature increases. The inlet temperature of the compressor needs to be maintained above the critical temperature 30.98 ℃, and the reduction of the inlet temperature of the compressor is beneficial to improving the cycle thermal efficiency.
Further, the invention also provides a supercritical carbon dioxide cycle power generation peak shaving method, which is based on the supercritical carbon dioxide cycle power generation peak shaving system of any one of the embodiments, and comprises the following steps: the main compressor 8 or the recompression 9 is arranged on a shaft connected with the turbine 1 and driven by the turbine 1, and the other compressors are connected with independent driving structures and are used for peak shaving of which the required peak shaving load is in the range of 30-100% of rated load.
Further, when the required peak load is 30% -55% of rated load, the main compressor 8 and the turbine 1 are arranged in a connecting shaft way, and the precompressor 5 and the recompressor 9 are respectively connected with independent driving structures; when the required peak load is 55% -100% of rated load, the recompressor 9 and the turbine 1 are arranged in a connecting shaft way, and the precompressor 5 and the main compressor 8 are respectively connected with independent driving structures.
Specifically, experiments have shown that when the inlet temperature of the turbine 1 is raised to 750 ℃ and the inlet temperatures of the three compressors are 35 ℃ by using high-temperature molten salt as a heat transfer medium, the operating efficiency of the partial cooling cycle of the turbine 1 and the main compressor 8 at 30% -100% load is 43.01% -49.85%, and the operating efficiency of the partial cooling cycle of the turbine 1 and the recompression 9 at 30% -100% load is 41.58% -50.38%.
Comparing the operation efficiency of the two mechanically arranged circulation systems of the turbine 1 under the variable load working condition, the efficiency advantage of deep peak regulation (30% -55% load) of the circulation response of the turbine 1 and the main compressor 8 in a connecting shaft arrangement is obvious, and the efficiency of the circulation of the turbine 1 and the recompression 9 in a connecting shaft arrangement is higher under higher load (55% -100% load). This is mainly due to the fact that the output work of the turbine 1 is hardly reduced when absorbing heat per unit at low loads of deep peak shaving and the cycle in which the turbine 1 is coupled to the main compressor 8 is lower and thus the cycle efficiency is higher at low loads.
Furthermore, the invention provides a specific regulation strategy of the supercritical carbon dioxide cycle power generation peak shaving system when the system is used for peak shaving, and the optimal operation parameters under different loads can be obtained in an optimized mode according to the regulation strategy. Specifically, when the arrangement of the main compressor 8 and the turbine 1 is adopted, the shaft rotational speeds of the main compressor 8 and the recompressor 9 gradually decrease and the shaft rotational speed of the precompressor 5 gradually increases as the required peak shaving load decreases.
Further, when the arrangement of the recompression machine 9 and the turbine 1 is adopted, the shaft rotation speed of the recompression machine 9 is gradually reduced, the shaft rotation speed of the main compressor 8 is gradually reduced and then increased, and the shaft rotation speed of the precompressor 5 is gradually increased as the required peak shaving load is reduced.
Further, in the process of changing the required peak shaving load, the shunt ratio of the system is kept unchanged; wherein the split ratio is the ratio of the flow of working medium of the main compressor 8 to the total flow of working medium of the main compressor 8 and the recompressor 9.
Specifically, when the cycle is actually operated, the high-temperature ternary chloride is heated and cooled by air, the inlet temperature of the turbine 1 is 750 ℃, the inlet temperatures of the three compressors are 35 ℃, the rated load is set under the design working condition, the power generation efficiency of the circulating system in which the turbine 1 and the main compressor 8 are arranged in a connecting shaft manner, namely the system shown in fig. 1, is 49.85%, and the power generation efficiency of the circulating system in which the turbine 1 and the recompression 9 are arranged in a connecting shaft manner, namely the system shown in fig. 2, is 50.38%. In the off-design mode, the maximum pressure, the minimum pressure, the intermediate cooling pressure and the split ratio of the circulation system can be adjusted by flexibly controlling the shaft speed of the individual compressors and the splitter valve 6, wherein the shaft speed of the turbine 1 is identical to the main compressor 8 or the recompressor 9.
For the cycle in which the turbine 1 is coupled to the main compressor 8, the main compressor 8 and the recompressor 9 shaft speeds decrease with decreasing load, but the precompressor 5 shaft speed increases with decreasing load, and the opening of the splitter valve 6 is almost unchanged. For the circulation of the turbine 1 and the recompression 9 which are arranged in a connecting shaft, the rotation speed of the recompression 9 shaft is reduced along with the reduction of the load, the rotation speed of the main compressor 8 shaft is firstly reduced, then the rotation speed of the precompressor 5 shaft is increased when the required peak load is lower than 50% of rated load, and the opening degree of the splitter valve 6 is almost unchanged.
The reason why the compressor shaft speed increases with decreasing load is mainly to cope with the increasing compressor specific enthalpy. Thus, the highest pressure, the lowest pressure and the intermediate cooling pressure of the cycle gradually decrease, and the split ratio is maintained at about 0.56 and remains almost unchanged. I.e. the split ratio may be 0.56.
Further, when the required peak shaving load is 30% -55% of the rated load, the turbine 1 and the main compressor 8 are arranged in a connecting shaft way, and in the load variation range, as the required peak shaving load is reduced, the shaft rotation speeds of the main compressor 8 and the recompressor 9 are gradually reduced, and the shaft rotation speed of the precompressor 5 is gradually increased.
Further, when the required peak shaving load is 55% -100% of the rated load, the turbine 1 and the recompressor 9 are arranged in a connecting shaft way, and in the load variation range, as the required peak shaving load is reduced, the shaft rotation speeds of the main compressor 8 and the recompressor 9 are gradually reduced, and the shaft rotation speed of the precompressor 5 is gradually increased.
Further, the invention aims to provide a supercritical CO which is suitable for efficient and flexible operation of peak shaving scenes 2 Mechanical optimization layout scheme of circulating turbine 1, which is designed based on supercritical carbon dioxide circulating systemAnd (3) relevant researches of parameter optimization and operation parameter regulation and control are carried out, an arrangement scheme and an operation parameter regulation and control strategy of the circulating equipment are determined, and the optimal operation parameters and operation efficiency of the circulation under partial load are obtained in an optimized mode.
In particular, the invention discloses a supercritical CO in peak shaving scene 2 Mechanical optimization of the circulation turbine 1, which is designed for supercritical CO in the form of partial cooling 2 The circulation is provided, and the circulation is composed of 1 turbine 1, 3 compressors, 2 regenerators, 1 heater and 2 air coolers, and the safe and efficient operation of the circulation under peak shaving working conditions is ensured by optimizing the arrangement scheme of the turbine 1 and the compressors. In particular, when the depth peak shaving requirement (load<55%) adopts a scheme that the turbine 1 is connected with the main compressor 8 and the main compressor 8 is driven by the turbine 1; while the changing load demand to be handled is relatively high (load>55%) adopts the scheme that the turbine 1 is connected with the recompressor 9 and the recompression 9 is driven by the turbine 1; meanwhile, the rest compressors are arranged in a split shaft mode and driven by independent motors; under a variable load working condition, the shaft rotating speed of the turbine 1 is regulated according to the shaft rotating speed of the continuous shaft compressor, and the shaft rotating speed of the other compressors is independently regulated according to the actual pressure ratio and the flow; the variable load operation parameters and efficiency of the circulation under the peak shaving scene can be obtained through optimization. The proposal considers the supercritical CO 2 The flexibility and the high efficiency of the circulation operation regulation and control under the variable load working condition are beneficial to improving the supercritical CO-based system 2 The power supply economy and reliability of the circulating high-temperature solar thermal power generation peak shaving power station.
Compared with the scheme that the turbine 1, the main compressor 8, the recompressor 9 and the precompressor 5 are all connected with the shaft, the invention is easier to flexibly regulate and control the rotation speed of the compressor shaft in a peak regulation scene, and realizes the deep peak regulation of circulation; compared with the scheme that the turbine 1, the main compressor 8, the recompressor 9 and the precompressor 5 are respectively arranged in a split shaft mode, the scheme provided by the invention has higher thermal efficiency under all working conditions, and can still meet the flexible regulation and control of the shaft rotation speed of mechanical equipment of each turbine 1 under variable working conditions; the invention is suitable for different types of peak regulation demands, and a more efficient mechanical arrangement scheme of the circulating turbine 1 is preferred, when the load demand is mostly 30% -55%, the circulating turbine 1 and the main compressor 8 are recommended to be arranged in a connecting way, and when the load demand is mostly 55% -100%, the circulating turbine 1 and the recompression 9 are recommended to be arranged in a connecting way. The following is further illustrated by specific examples and comparative examples:
specific example 1:
as shown in FIG. 1, supercritical CO in example 1 of the present invention 2 The mechanical arrangement scheme of the circulating turbine 1 is that the turbine 1 is connected with a main compressor 8 in a shaft way, the main compressor 8 is directly driven by the turbine 1, and a compressor 9 and a precompressor 5 are respectively arranged in a shaft way and driven by independent motors. The rated power of the cycle is 100MW, the highest, lowest, intermediate cooling pressure and split ratio of the cycle obtained under the 100% rated load are 25MPa,5.75MPa,8.38MPa and 0.561 respectively, the shaft rotation speed of the turbine 1 and the main compressor 8 is 15500rpm, the shaft rotation speed of the re-compressor 9 is 18700rpm, the shaft rotation speed of the precompressor 5 is 4100rpm, and the rated power generation efficiency of the cycle is 49.85%.
Specific example 2:
as shown in fig. 1, example 2 of the present invention was the same as the cycle employed in example 1. In peak regulation, the cyclic output power needs to be regulated according to the changing load demand, the shaft rotation speed of the turbine 1 and the shaft rotation speed of the main compressor 8 are regulated and controlled in real time, and the shaft rotation speeds of the compressor 9 and the precompressor 5 are independently regulated. When the load demand was reduced to 30% of the rated value, the highest, lowest, intermediate cooling pressure and split ratio of the cycle were adjusted to 10.44mpa,4.04mpa,7.49mpa and 0.560, respectively, and the power generation efficiency of the cycle was reduced to 43.01%.
Specific example 3:
as shown in FIG. 2, supercritical CO in example 3 of the present invention 2 The mechanical arrangement scheme of the circulating turbine 1 is that a recompressor 9 is connected with the turbine 1 in a shaft way, the recompressor 9 is directly driven by the turbine 1, and a precompressor 5 and a main compressor 8 are arranged in a split shaft way and are respectively driven by independent motors. The rated power of the cycle is 100MW, the highest, lowest and intermediate cooling pressures of the cycle obtained under 100% rated load and the split ratio are 25MPa,5.56MPa,8.40MPa and 0.561 respectively, and the shaft speeds of the turbine 1 and the recompression 9 are 19000rpm, the shaft speed of the main compressor 8 was 15600rpm, the shaft speed of the precompressor 5 was 4400rpm, and the cycle rated power generation efficiency was 50.38%.
Specific example 4:
as shown in fig. 2, example 4 of the present invention was the same as the cycle employed in example 3. In the peak regulation scene, the shaft rotation speed of the turbine 1 and the shaft rotation speed of the recompression 9 are regulated in real time, and the shaft rotation speeds of the main compressor 8 and the precompressor 5 are independently regulated. When the load demand was reduced to 30% of the rated value, the highest, lowest, intermediate cooling pressure and split ratio of the cycle were adjusted to 11.03mpa,4.16mpa,7.23mpa and 0.557, respectively, and the power generation efficiency of the cycle was reduced to 41.58%.
Comparative example 1:
as shown in FIG. 3, comparative example 1 of the present invention is supercritical CO 2 The whole part-shaft arrangement of the circulating turbine 1 is realized in a scheme that the turbine 1 is directly connected with a generator to generate electricity, and the compressor 9, the precompressor 5 and the main compressor 8 are respectively driven by independent motors. The rated power of the cycle is still 100MW, the highest, lowest and intermediate cooling pressure and the split ratio of the cycle obtained under the 100% rated load are 25MPa,5.73MPa,8.51MPa and 0.561 respectively, and the rated power generation efficiency of the cycle is 49.21%.
Comparative example 2:
as shown in FIG. 3, comparative example 2 of the present invention was the same as the cycle employed in comparative example 1. Under the peak regulation scene, the shaft rotation speed of each turbine 1 machine is independently regulated and controlled. When the load demand was reduced to 30% of the rated value, the highest, lowest, intermediate cooling pressure and split ratio of the cycle were adjusted to 11.05mpa,3.81mpa,7.28mpa and 0.558, respectively, and the power generation efficiency of the cycle was reduced to 40.69%.
Comparative example 3:
as shown in FIG. 4, the supercritical CO in comparative example 3 of the present invention 2 The mechanical arrangement scheme of the circulating turbine 1 is that the turbine 1 is connected with the precompressor 5 in a shaft way, the precompressor 5 is directly driven by the turbine 1, the main compressor 8 and the recompressor 9 are respectively arranged in a split shaft way, and the main compressor and the recompressor are driven by independent motors. The rated power of the cycle is still 100MW, and the highest, lowest and intermediate cooling of the cycle is optimally obtained under 100% rated loadThe pressure and the split ratio are respectively 25MPa,5.12MPa,8.57MPa and 0.561, and the cycle rated power generation efficiency is 50.10%.
Comparative example 4:
as shown in FIG. 4, comparative example 4 of the present invention was the same as the cycle employed in comparative example 3. In peak regulation, the shaft rotation speed of the turbine 1 and the shaft rotation speed of the precompressor 5 are regulated in real time, and the shaft rotation speeds of the main compressor 8 and the recompressor 9 are regulated independently. When the load demand was reduced to 30% of the rated value, the highest, lowest, intermediate cooling pressure and split ratio of the cycle were adjusted to 11.36mpa,4.46mpa,6.76mpa and 0.562, respectively, and the power generation efficiency of the cycle was reduced to 39.63%.
As can be seen from the analysis and comparison of the specific examples and comparative examples, two types of supercritical CO proposed by the present invention are adopted 2 The mechanical optimization arrangement scheme of the circulating turbine 1 can better give consideration to the flexibility and the high efficiency of the circulation under the peak shaving operation scene. Compared with the scheme of the whole split shaft arrangement of the turbine 1 machinery, the scheme of the coupling arrangement of the turbine 1 and the precompressor 5 and the like, the scheme of the coupling arrangement of the turbine 1 and the recompressor 9 can further improve the power generation efficiency, and the absolute value of the power generation efficiency under rated load can be respectively improved by 1.17% and 0.28%. When the deep peak regulation requirement is met, the efficiency advantage of the scheme of the coupling arrangement of the turbine 1 and the main compressor 8 is obvious, and if the load is 30% of the rated value, the cycle power generation efficiency can still reach 43.01%, and compared with the scheme of the whole split shaft arrangement of the turbine 1, the coupling arrangement of the turbine 1 and the precompressor 5 and the coupling arrangement of the turbine 1 and the recompressor 9, the absolute value of the cycle efficiency can be respectively improved by 2.32%,3.38% and 1.43%.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (10)
1. The utility model provides a supercritical carbon dioxide circulation electricity generation peak shaving system which characterized in that, supercritical carbon dioxide circulation electricity generation peak shaving system's turbomachinery includes turbine, precompressor, main compressor and recompression, wherein main compressor or recompression with the turbine connecting shaft arrangement, by the turbine drives, the other compressors are connected with independent drive structure.
2. The supercritical carbon dioxide cycle power generation peak shaver system according to claim 1, wherein when the required peak shaver load is 30% -55% of rated load, the main compressor and the turbine are arranged in a connecting shaft, and the precompressor and the recompressor are respectively connected with independent driving structures;
when the required peak regulating load is 55% -100% of the rated load, the recompressor and the turbine are arranged in a connecting shaft way, and the precompressor and the main compressor are respectively connected with independent driving structures.
3. The supercritical carbon dioxide cycle power generation peak shaving system of claim 1, wherein the supercritical carbon dioxide cycle power generation peak shaving system further comprises: the device comprises a high-temperature heat regenerator, a low-temperature heat regenerator, a pre-cooler, a flow dividing valve, an intercooler and a heater;
the outlet of the turbine is connected with the first inlet of the high-temperature heat regenerator, the first outlet of the high-temperature heat regenerator is connected with the first inlet of the low-temperature heat regenerator, the second outlet of the high-temperature heat regenerator is connected with the inlet of the heater, the outlet of the heater is connected with the inlet of the turbine, the first outlet of the low-temperature heat regenerator is connected with the inlet of the pre-cooler, the outlet of the pre-cooler is connected with the inlet of the pre-compressor, the outlet of the pre-compressor is connected with the inlet of the intercooler and the inlet of the recompressor respectively through the shunt valve, the outlet of the intercooler is connected with the inlet of the main compressor, the outlet of the main compressor is connected with the second inlet of the low-temperature heat regenerator, the second outlet of the low-temperature heat regenerator is connected with the second inlet of the high-temperature heat regenerator, and the outlet of the recompression is connected with the second inlet of the high-temperature heat regenerator.
4. The supercritical carbon dioxide cycle power generation peak shaving system of claim 3, wherein the heating medium in the heater is molten salt; the split ratio of the split valve is 0.5-0.6.
5. The supercritical carbon dioxide cycle power generation peak shaver system according to claim 1, wherein the inlet medium temperature of the turbine is 600 ℃ or higher; the inlet medium temperatures of the pre-compressor, the main compressor and the recompressor are each greater than 30.98 ℃.
6. A supercritical carbon dioxide cycle power generation peak shaving method, characterized in that it is based on the supercritical carbon dioxide cycle power generation peak shaving system as defined in any one of claims 1 to 5, comprising:
the main compressor or the recompression is connected with the turbine through a shaft, the turbine is driven, and other compressors are connected with an independent driving structure and used for peak shaving of which the required peak shaving load is in the range of 30% -100% of rated load.
7. The method of claim 6, wherein the main compressor is arranged in conjunction with the turbine when the peak load is 30% -55% of the rated load, and the precompressor and the recompressor are connected to separate driving structures;
and when the required peak load is 55-100% of the rated load, arranging the recompressor and the turbine connecting shaft, and respectively connecting the precompressor and the main compressor with independent driving structures.
8. The supercritical carbon dioxide cycle power generation peaking method of claim 6, wherein when the main compressor and turbine coupling arrangement is employed, the shaft speeds of the main compressor and the recompressor gradually decrease and the shaft speed of the precompressor gradually increases as the required peaking load decreases.
9. The supercritical carbon dioxide cycle power generation peaking method of claim 6, wherein when the re-compressor and turbine coupling arrangement is employed, the shaft speed of the re-compressor gradually decreases and then increases, and the shaft speed of the pre-compressor gradually increases as the required peaking load decreases.
10. The method for peak shaving of supercritical carbon dioxide cyclic power generation according to claim 6, wherein the split ratio of the system is kept unchanged during the process of changing the required peak shaving load; wherein the split ratio is the ratio of the working medium flow of the main compressor to the total working medium flow of the main compressor and the recompressor.
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