CN110274218A - Method and power station from the power station production electric power run under the loading condiction of variation - Google Patents

Abstract

The present invention relates to the field of power generation, and in particular to a method and power station for producing power from a power station operating under varying load conditions. The power station includes a boiler, a steam turbine unit equipped with a boiler feedwater preheating system, a _CO2 capture system and a thermal energy storage system, wherein the method includes: when the power station is operating under low load conditions, from the The boiler feedwater preheating system draws a portion of the boiler feedwater for storage in the TES system, and allows the thermal energy used for absorbent regeneration in the _CO2 capture system to be partially or fully supplied from the boiler feedwater stored in the TES system. The present invention solves the problem of limited thermal energy extraction by extracting energy from boiler feedwater, employing a TES system to store thermal energy during low-load operation phases and release thermal energy during high-load operation phases to compensate for steam extraction for absorbent regeneration, which can be more Good control of the steam cycle system and widened dynamic range of operation.

Description

Method and development of electricity production from a power station operating under varying load conditions power station

technical field

The present invention relates to the field of power generation, and in particular to a method and power station for producing power from a power station operating under varying load conditions.

Background technique

One of the ways to capture CO ₂ in coal-fired power plants is to use absorbents to capture CO ₂ from flue gas. For example, _CO2 -containing flue gas is passed through a _CO2 scrubber and contacted with an absorbent capable of absorbing _CO2 , so that _CO2 in the flue gas is absorbed to obtain flue gas with reduced _CO2 content, and the resulting _CO2 -rich absorption The agent can be reused after regeneration.

This absorbent-based _CO capture technology requires thermal energy to regenerate the absorbent. Typically the thermal energy required for a coal fired power station is 2-4 GJ/tonne _CO2 , depending on factors such as the chemistry of the absorbent.

A steam cycle power plant typically includes at least two steam turbines operating in series. Among them, the high pressure steam is sent to a high pressure (HP) steam turbine to generate electricity, and the waste steam of the HP turbine is sent to a low pressure (LP) steam turbine to generate electricity. In some cases, steam cycle power plants are also equipped with intermediate pressure (IP) steam turbines to utilize the waste steam of the HP turbine and send the generated waste steam to the LP steam turbine. For power plants with _CO2 absorbent systems, the current approach is to extract steam from one or more of these turbines to provide the thermal energy required for absorbent regeneration. Currently being piloted at some coal-fired power stations, it also includes means of extracting steam from medium-pressure steam turbines.

The use of steam in a power station to provide the thermal energy required for absorbent regeneration generally has two disadvantages. One is that such an operation will reduce the amount of steam used to generate electricity, thereby reducing the overall power output of the power station and reducing the amount of electricity generated. Net thermal efficiency of the station. The second disadvantage is that steam will be drawn from one or more extraction points of a steam turbine, which will reduce the total mass flow downstream of the turbine at the extraction point, which in turn reduces the output of the turbine, making the turbine more difficult to control. In addition, a minimum amount of steam is required to maintain the operation of the steam turbine, which means that there is a practical limit to the extraction of energy by means of steam extraction.

Considering the high demand for renewable energy in the grid system, fossil fuel thermal power plants need to face the situation of operating under changing load, including low load operation for a long period of time. The changing load makes the operation of the power station more difficult to control, and the operation of the system that needs to extract steam to the _CO2 capture system is more difficult to operate under the changing load. Under high load operation, it is advantageous for the power station to use more thermal energy to generate more electrical energy than to use it elsewhere, however, the demand for more thermal energy generated by fuel combustion also means more The production of _CO2 , in turn, requires more thermal energy to regenerate the absorbent used to capture _CO2 from the flue gas. On the other hand, during low load operation, the power station needs less thermal energy to meet the power demand, resulting in the power station usually operating at a lower than rated power output during this phase.

Numerous studies are currently underway to evaluate the methodological feasibility of extracting value from _CO capture systems operating under varying load conditions. One approach would be to store the _CO2 -rich absorbent during high-load operation and regenerate it during low-load operation, which would allow steam extraction to match the electricity production demand curve. However, this method requires additional space for the absorbent, and requires a device for absorbent storage and an extraction system, and is therefore not preferred. Also, _CO2 -rich absorbents generally degrade at a higher rate than _CO2 -lean absorbents, so storing rich absorbents will result in faster loss of absorbent and thus higher costs.

Another approach involves capturing CO ₂ only if the emissions value (or regulatory penalty) can match the operational capture system. There are times when this approach is not feasible, such as when regulatory bodies require total absolute _CO2 emissions to stay below a certain level consistently or set absolute _CO2 emissions caps.

US 9,617,915 B2 discloses the use of thermal energy storage (TES) devices to compensate for absorbent regeneration in a combined cycle power generation system. Among them, standard combined cycle power generation systems include gas turbines with attached steam turbines. In this method, the heat energy of the exhaust gas of the gas turbine is used to generate steam in a waste heat recovery steam generator and used to start the steam turbine. In US9,617,915B2, the thermal energy extracted to the steam released by the steam turbine is stored in the TES system when the power station is in low load mode, and the stored thermal energy is released when the power station is in high load mode . In this way, the TES system will divert thermal energy from the low load phase to the high load phase for absorbent regeneration in the capture system, so that more energy is available to generate electricity than for CO during times of high demand for electricity ₂ capture system.

In US 9,617,915 B2, the TES system is supplemented with thermal energy directly by the steam coming out of the steam turbine, which means the steam exhausted by the HP turbine, IP turbine and LP turbine. It will be understood by those skilled in the art that the method can only use the steam exhausted from the HP and IP turbines, as they have a sufficiently high temperature to regenerate the absorbent without additional heating. The temperature of the steam discharged from the LP steam turbine is too low to regenerate the absorbent without additional heating. Thermal energy extraction from HP and IP turbines is limited by the maintenance of turbine operation downstream of the steam extraction point even during low load operating phases. Reducing the mass flow will result in necessarily having an upper limit on the thermal energy extracted thereby making the process difficult to control, reducing efficiency, and even in extreme cases causing the outage of the steam turbine downstream of the extraction point.

Other existing technologies include (1) separate generation of thermal energy for absorbent regeneration (eg using concentrated solar power or supplemental boilers); and (2) solar preheating of boiler feed water using thermal energy storage to compensate for power generation. The drawbacks of these methods are that they require additional equipment and operating steps, and the thermal energy storage (TES) systems therein are only used to convert loads and production in concentrating solar power (CSP). These solar thermal methods are limited by the efficacy of solar collectors, which in turn are limited by local solar insolation (usually around 200W/ ^m2 ). When the insolation is 200W/ ^m2 , and assuming 100% efficiency of light-to-heat conversion, an area of at least ^0.1km2 needs to generate 20MW of heat energy.

Therefore, there is a need in the art to control power generation from power plants to meet peak power demand, while being able to accommodate parasitic power loads resulting from the introduction of _CO2 capture systems to control power plant exhaust emissions. At times of peak power demand, parasitic loads on the _CO capture system will typically limit the maximum output of the power plant. In some cases, the net power output will be lower than the demand power. The ability to increase power output for this purpose is required at this time. In fact, extraction of steam from a steam turbine has a negative effect on the efficiency and controllability of the system. Therefore, it is necessary to provide a method of extracting and storing thermal energy to reduce these adverse effects. There is also a need to improve the economics of the overall _CO2 capture system for power plants operating under varying loads by utilizing the thermal energy stored under low load operation to recover _CO2 under high load operation. More specifically, the choice to store thermal energy during low load operating phases of low power demand will suffer from thermal energy extraction quantity and quality (temperature) limitations that will be directly affected by the way energy is extracted from the steam of the steam cycle.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a novel method and power station for producing electricity from a power station operating under varying load conditions, wherein the method can improve the overall output of the power station and reduce the cost of operating a _CO capture system cost.

In order to achieve the above objects, one aspect of the present invention provides a method of producing electricity from a power plant operating under varying load conditions, the power plant comprising a boiler, a steam turbine unit equipped with a boiler feedwater preheating system, a _CO2 capture system and thermal energy storage (TES) systems,

Wherein, the method includes: extracting part of boiler feedwater from the boiler feedwater preheating system to store in the TES system when the power station is operating under low load conditions, and allowing the absorbent in the _CO2 capture system Some or all of the thermal energy used for regeneration is supplied from boiler feed water stored in the TES system.

A second aspect of the present invention provides a power plant with a _CO capture system, the power plant comprising: a boiler, a steam turbine unit equipped with a boiler feed water preheating system, a _CO capture system and a thermal energy storage (TES) system;

Wherein, the TES system is connected to the boiler feedwater preheating system and the _CO2 capture system, so that when the power station operates under low load conditions, part of the boiler feedwater is extracted from the boiler feedwater preheating system for storage to TES The thermal energy used to regenerate the absorbent in the _CO2 capture system is partially or fully supplied from boiler feed water stored in the TES system.

The present invention addresses the problem of limited thermal energy extraction by extracting energy from boiler feedwater. The thermal energy stored during the low load operation phase will be used to recover CO ₂ during the high load operation phase. The use of a thermal energy storage system to store thermal energy during periods of low load operation and release it to compensate for steam extraction for absorbent regeneration during periods of high load operation has the advantage of better control of the steam cycle and a wider dynamic range of operation. The stored thermal energy can partially or completely replace the steam extracted for the regeneration of the absorbent in the high load stage. In particular, the method encompassed by the present invention will more efficiently extract thermal energy during periods of low power demand and be used to improve the overall power plant output during periods of high power demand.

Description of drawings

Figure 1 schematically illustrates a preferred embodiment of a method of generating electricity from a power plant operating under varying load conditions according to the present invention.

Figure 2 schematically illustrates one embodiment of a method of generating electricity from a power plant operating under varying load conditions according to the prior art.

Description of reference numerals

1: Boiler; 2: HP Steam Turbine; 3: IP Steam Turbine; 4: LP Steam Turbine; 5: Condenser; 6: First Preheater; 7: Degasser; 8: Second Preheater; 9 : _CO2 absorber; 10: _CO2 regenerator; 11: first storage tank; 12: heat exchanger; 13: second storage tank;

101: Raw water; 102: Carbon fuel; 103: HP steam; 104: IP steam I; 105: IP steam II; 106: LP steam; 107: Second LP steam; 108: First LP steam; 109: Waste steam ; 113: flue gas; 114: CO ₂ lean flue gas; 115: CO ₂ rich absorbent; 116: CO ₂ desorption; 117: CO ₂ lean absorbent; 119: first stream; 120: third stream; 121: Fourth stream; 122: Condensate stream; 123: Second stream; 124: Fifth stream; 118: Sixth stream.

Detailed ways

The endpoints of ranges and any values disclosed herein are not limited to the precise ranges or values, which are to be understood to encompass values proximate to those ranges or values. For ranges of values, the endpoints of each range, the endpoints of each range and the individual point values, and the individual point values can be combined with each other to yield one or more new ranges of values that Ranges should be considered as specifically disclosed herein.

One aspect of the present invention provides a method of producing electricity from a power plant operating under varying load conditions, the power plant comprising a boiler, a steam turbine unit equipped with a boiler feed water preheating system, a _CO capture system and thermal energy storage (TES). )system,

Wherein, the method includes: extracting part of boiler feedwater from the boiler feedwater preheating system to store in the TES system when the power station is operating under low load conditions, and allowing the absorbent in the _CO2 capture system Some or all of the thermal energy used for regeneration is supplied from boiler feed water stored in the TES system.

According to the present invention, the method of generating electricity can be applied to any power station including a boiler, a steam turbine unit equipped with a boiler feedwater preheating system and a _CO2 capture system, whereby the additional TES system will compensate for _CO2 The large amount of thermal energy required by the capture system is especially during high load operating conditions. Such power plants may be power plants using carbonaceous fuels such as coal or natural gas, specific examples of which are the coal-fired Rankine cycle or the natural gas combined cycle.

In accordance with the present invention, the method of the present invention can extract thermal energy by extracting boiler feed water from the boiler water preheating system, and using the TES system to store and release this thermal energy to compensate for the steam used to regenerate the absorbent extraction to the steam cycle system. The steam turbine unit is a device suitable for generating electricity using steam under pressure and high temperature produced by a boiler. For this reason, the steam turbine unit is a key device of the power plant, which determines the electrical output of the entire power plant. Typically, the steam turbine may comprise a high pressure (HP) steam turbine, an intermediate pressure (IP) steam turbine, a low pressure (LP) steam turbine, or any combination thereof, in order to improve the overall power output of the power plant, preferably, the The steam turbine unit includes a high pressure (HP) steam turbine, an intermediate pressure (IP) steam turbine and a low pressure (LP) steam turbine.

Typically, the steam extracted from the IP/LP junction is used to regenerate the absorbent in the _CO2 capture system. Because the method of the present invention will utilize at least part of the thermal energy provided by the TES system to regenerate the absorbent during operation under high load conditions, the LP steam drawn from the steam turbine unit to regenerate the absorbent during such high load operation will be reduced or exempt. While during low load condition operation, a limited amount of steam from the IP/LP interface should be extracted from the steam turbine unit for regeneration of the absorbent in the _CO2 capture system. In this case, preferably, LP steam is extracted from the IP/LP interface under low load conditions to provide thermal energy for absorbent regeneration in the _CO capture system, and at high load conditions for use in the CO capture system ₂ The thermal energy to regenerate the absorbent in the capture system includes the thermal energy stored in the TES system.

As shown in Figure 1, the HP steam turbine 2, IP steam turbine 3 and LP steam turbine 4 are usually connected in series, if all steam turbines can be operated at substantially full rated capacity, the total output of the power station will be very high. Extracting steam from the system will reduce the electrical output of the overall system and also reduce the thermal efficiency of the overall system. Changing the amount of steam extraction in response to changes in power demand will result in a system that is difficult to control. Therefore, what is needed in the art is for a steam turbine unit to operate smoothly and to operate at substantially full rated capacity during periods of high power demand. To achieve this, the method of the present invention employs a TES system to store thermal energy during periods of low power demand and release thermal energy during periods of high power demand to compensate for absorbent regeneration so that more LP steam can be used in the LP steam turbine to generate electricity, whereby the steam turbine can be controlled to operate at almost full rated capacity to generate more electricity.

In one embodiment of the present invention, in the case where the steam turbine unit comprises a high pressure (HP) steam turbine, an intermediate pressure (IP) steam turbine and a low pressure (LP) steam turbine, as shown in FIG. 1 , preferably Ground, the method of the present invention will comprise:

(1-1) The HP steam 103 generated by the boiler is sent to the HP steam turbine 2 to generate electricity and obtain intermediate pressure (IP) steam;

(1-2) Sending the IP steam to the IP steam turbine 3 to generate electricity and obtain low pressure (LP) steam 106;

(1-3) Sending part of the LP steam 106 as the first LP steam 108 to the LP steam turbine 4 to generate electricity and obtain the waste steam 109;

(1-4) Sending the remaining part of the LP steam 106 as the second LP steam 107 to the CO ₂ capture system for thermal energy exchange to regenerate the absorbent and obtain condensed water D;

Among them, waste steam 109 and condensed water D will be sent to the boiler water preheating system to be heated and circulated into the boiler.

It should be understood that in the present invention, less or almost no LP steam is required for absorbent regeneration during the high load operating phase, while the amount of second LP steam 107 will be relatively higher during the low load operating phase or for normal dosage.

Preferably, the high load conditions refer to conditions in which the power station requires the steam turbine units to operate above 75% of rated capacity, and the low load conditions refer to the power station that requires the steam turbine units to operate below 75% operating conditions at the rated capacity.

In order to improve the efficacy of the IP steam turbine 3, preferably, the IP steam defined as IP steam I104 will be returned to the boiler for reheating, and obtain a relatively higher temperature IP steam defined as IP steam II105, which will then be It is sent to IP steam turbine 3 to generate electricity.

According to the present invention, the HP steam turbine, the IP steam turbine and the LP steam turbine may be conventionally known steam turbines in the art. Generally, the HP steam turbine refers to a turbine that can be applied to steam with a pressure above 23 MPa, so The IP steam turbine refers to a turbine that can be applied to steam with a pressure of 5-6 MPa, and the LP steam turbine refers to a turbine that can be applied to steam with a pressure of 1.2 MPa or less.

According to the present invention, the boiler feed water preheating system fitted to the steam turbine unit is for preheating the condensate and waste steam generated by the steam turbine and circulating the preheated boiler feed water to the boiler to generate steam again System, preferably, the boiler feed water preheating system includes a condenser 5 , a first preheater 6 , a degasser 7 and a second preheater 8 . In the case where the steam turbine unit includes a high pressure (HP) steam turbine, an intermediate pressure (IP) steam turbine and a low pressure (LP) steam turbine, as shown in FIG. 1 , wherein the condensate D and waste steam 109 Mixing is carried out in the condenser 5 to obtain boiler feed water I;

The boiler feedwater I will be heat-exchanged with steam from the LP steam turbine 4 in the first preheater 6 (which may be a series of low temperature boiler feedwater preheaters in series) to obtain boiler feedwater II;

The boiler feed water II will undergo heat exchange with the steam from the IP steam turbine 3 in the degasser 7 and obtain boiler feed water III;

The boiler feedwater III will be heat-exchanged with steam from the IP steam turbine 3 and the HP steam turbine 2 in the second preheater 8 (which may be a series of high temperature boiler feedwater preheaters in series) and obtain sufficient Preheated boiler feed water IV;

And the boiler feed water IV is sent to the boiler to produce steam.

The present invention has no particular limitations on the condenser 5, the first preheater 6, the deaerator 7 and the second preheater 8, and they can be the condensers, Heater and degasser, wherein the first 6 and second 8 preheaters will preheat boiler feed water with steam extracted from HP, IP and LP steam turbines.

Preferably, the steam extracted from the second preheater 8 and after heat exchange with the boiler feed water III is sent to the deaerator 7 together with the steam extracted from the IP steam turbine 3 and Heat exchange with boiler feed water II is carried out in said deaerator 7 to obtain boiler feed water III.

Preferably, the steam extracted from the degasser 7 and heat-exchanged with the boiler feed water II is sent to the first preheater 6 together with the steam extracted from the LP steam turbine 4 and at The first preheater 6 conducts heat exchange with the boiler feed water I to obtain boiler feed water II.

Preferably, the steam extracted from the first preheater 6 and after heat exchange with the boiler feed water I is sent to the condenser 5 to be mixed with the condensed water D and the waste steam 109 to obtain Boiler feed water I so that the water in condenser 5 is preheated with steam from first preheater 6 .

According to the present invention, the power plant will operate under dynamic load conditions, so that the TES system can use the thermal energy stored during operation under low load conditions to compensate for the regeneration of the absorbent in the _CO capture system under high load conditions. thermal energy, however when the power station is operating under low load conditions, the TES system can also extract boiler feed water from the boiler feed water preheating system and provide thermal energy to regenerate the absorbent in the _CO capture system, only during this period, the extraction from The amount of boiler feed water of the boiler feed water preheating system and sent to the TES system will be higher than the amount of water drawn from the TES system to provide thermal energy for the _CO2 capture system.

Without being bound by any theory, preferably, when the power station is operating under high load conditions, more of the heat source in the TES system will be used to provide heat energy to regenerate the absorbent in the _CO capture system, thereby increasing Little or no use of LP steam to regenerate the absorbent; and when the power station is operating under low load conditions, more boiler feed water will be sent to the TES system to store thermal energy, and less or no use of The heat source in the TES system will be used to provide thermal energy to regenerate the absorbent in the _CO capture system. This means that the TES system will store more boiler feedwater during plant operation in low load conditions, while this stored boiler feedwater will provide thermal energy for absorbent regeneration during plant operation in high load conditions.

According to the present invention, the TES may be constructed in a suitable manner to obtain the above-mentioned functions, preferably, as shown in FIG. 1 , the TES system includes a first storage tank 11 , a heat exchanger 12 and a second storage tank 13 . In this case, during low load conditions, part of the boiler feed water is sent to the first storage tank 11 as a heat source for storage, and during high load conditions, part of the heat source in the first storage tank 11 is used as a heat source. The first stream 119 is sent to the heat exchanger 12 for heat exchange with the third stream 120 from the second storage tank 13, wherein the first stream 119 will form a second stream after the exchange releases heat energy Stream 123, and said third stream 120 will produce a steam stream (ie, fourth stream 121 ) after heat exchange has absorbed thermal energy;

The fourth stream 121 will be sent to the _CO capture system to provide thermal energy for absorbent regeneration to form condensate (ie, condensate stream 122) and returned to the second storage tank 13; the second stream 123 will Return to the first storage tank 11 . It should be noted that the temperature of the first stream 119 should be higher than the temperature of the third stream 120 and the second stream 123, and the temperature of the fourth stream 121 should be higher than the temperature of the condensate stream 122. The third stream 120, fourth stream 121 and condensate stream 122 may be formed from thermal boiler feed water.

According to the present invention, in order to save water and improve the mass flow of the recycled boiler feed water, preferably, part of the water in the first storage tank 11 is sent to the condenser 5 as the fifth stream 124 to be combined with the condensation Water D is mixed with the waste steam 109 to obtain the boiler feed water I. That is, the boiler feed water I of the present invention can be composed of the steam extracted from the first preheater 6 and after heat exchange with the boiler feed water I, the condensed water D, the waste steam 109 and the fifth stream 124 mixed.

According to the present invention, when the first storage tank 11 is returned to the fifth stream 124 to form boiler feed water I, preferably, the method of the present invention comprises combining the fifth stream 124 with condensed water D and waste steam 109 in the condenser 5 was mixed to obtain boiler feed water I. Wherein, the condensed water D and the waste steam 109 can be directly sent to the condenser 5 for combination, or as shown in FIG. to condenser 5 to mix with fifth stream 124.

According to the present invention, as described above, the TES system can provide thermal energy for the regeneration of the absorbent of the _CO capture system based on the regeneration of the absorbent in the _CO capture system under high load conditions. The total thermal energy, the ratio of thermal energy provided by the TES system for regenerating the absorbent is at least 25%, preferably at least 50%, for example 50-100%, 60-80%, 70-90%, 85-100% . Wherein, the boiler feed water can be extracted from any point of the boiler feed water preheating system to be sent to the TES system, as long as the extracted boiler feed water is hot enough to generate saturated steam of 60 psia, for example, the degasser 7 part of the boiler feedwater in the line of the boiler feedwater III, part of the boiler feedwater in the line of the boiler feedwater III, part of the boiler feedwater in the line of the second preheater 8, part of the boiler feedwater in the line of the boiler feedwater IV, or any combination thereof from the boiler feedwater The preheating system is extracted and sent to the TES system as a heat source, preferably, based on the total amount of the boiler feedwater (usually referred to as boiler feedwater IV), extracted from the boiler feedwater preheating system and sent to the TES system The amount of boiler feed water in 1-50 vol%, preferably 10-40 vol%.

Preferably, the boiler feedwater preheating system includes a deaerator (as described above), and the method includes withdrawing a portion of the boiler feedwater from the deaerator to the TES system for storage as a heat source. More preferably, the amount of boiler feed water drawn from the degasser and sent to the TES system is 1-90 wt%, preferably 10-85 wt%, based on the total amount of boiler feedwater in the degasser weight%.

According to the present invention, the _CO2 capture system generally includes a _CO2 absorber 9 and a _CO2 regenerator 10, as shown in Figure 1, in which case the method of the present invention will comprise the following steps:

The flue gas 113 from the boiler 1 is sent to the _CO2 absorber 9 containing absorbent to absorb the CO2 in the flue gas 113 and obtain the _CO2 -lean flue gas 114 and the _{CO2 -} rich absorbent 115;

The CO ₂ rich absorbent 115 is sent to the CO ₂ regenerator 10 to regenerate the absorbent and obtain a CO ₂ lean absorbent 117 to circulate into the CO ₂ absorber 9 and to desorb CO ₂ 116 .

In the above case, the flue gas 113 is typically produced by burning carbonaceous fuel 102 in the boiler 1 to produce HP steam, and the flue gas contains large amounts of CO ₂ and possibly other waste gases. The absorbent in the CO ₂ absorber 9 can be any absorbent suitable for absorbing CO ₂ in the art, preferably a solvent, that is, the CO ₂ capture system uses a solvent as an absorbent to absorb CO ₂ . The solvent can be selected from one or more of amine compounds, such as monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), diisopropanolamine (DIPA), diethylene glycolamine ( DGA), N-methylethanolamine (MDEA), amino silicone oil, piperazine (PZ) or any mixture thereof.

In the above case, the CO ₂ lean flue gas 114 will be discharged from the CO ₂ absorber 9 and the CO ₂ rich absorbent 115 will be sent to the CO ₂ regenerator 10 for regeneration. As mentioned above, the thermal energy provided to the _CO2 capture system will be substantially provided to the _CO2 regenerator 10 to regenerate the absorbent so that the TES system and the lines of the second LP steam 107 will be connected to the CO2 regenerator 10. ₂ A regenerator 10 is connected to provide it with thermal energy. Wherein, after the absorbent regeneration is completed, the desorbed CO ₂ 116 will be discharged directly from the CO ₂ regenerator 10 , and the CO ₂ rich absorbent 115 will be restored to the CO ₂ lean absorbent 117 and recycled to the CO ₂ The absorber 9 is cyclically used to absorb CO ₂ in the flue gas.

A second aspect of the present invention provides a power plant with a _CO capture system, the power plant comprising: a boiler, a steam turbine unit equipped with a boiler feed water preheating system, a _CO capture system and a thermal energy storage (TES) system;

Wherein, the TES system is connected to the boiler feedwater preheating system and the _CO2 capture system, so that when the power station operates under low load conditions, part of the boiler feedwater is extracted from the boiler feedwater preheating system for storage to TES The thermal energy used to regenerate the absorbent in the _CO2 capture system is partially or fully supplied from boiler feed water stored in the TES system.

According to the present invention, the power plant will be suitable for the above-described method of the present invention, for which reason the above description of the method is incorporated by reference into the power plant description herein.

As mentioned above, in a preferred embodiment of the present invention, the steam turbine unit comprises a high pressure (HP) steam turbine, an intermediate pressure (IP) steam turbine and a low pressure (LP) steam turbine, and the IP/LP interface is is connected to the _CO2 capture system such that LP steam is extracted from the IP/LP interface under low load conditions to provide thermal energy for absorbent regeneration in the _CO2 capture system.

Wherein, the HP steam turbine 2 is used to expand the HP steam 103 generated by the boiler to generate electricity, and obtain intermediate pressure steam IP steam;

The IP steam turbine 3 is used to expand IP steam to generate electricity and obtain low pressure LP steam 106;

The LP steam turbine 4 is used to expand part of the LP steam 106 as the first LP steam 108 to generate electricity and obtain waste steam 109;

The _CO2 capture system is connected to the steam turbine unit to regenerate the absorbent with the thermal energy provided by the heat exchange of the remaining portion of the LP steam 106 defined as the second LP steam 107 and will form condensate after the heat exchange D;

The line of waste steam 109 and the line of said condensate D will communicate with the boiler feed water preheating system to heat them in the boiler feed water preheating system and circulate to said boiler 1 .

In order to be able to improve the efficiency of the IP steam turbine 3, preferably, the line of IP steam defined as IP steam I104 will communicate with the steam inlet of the boiler 1 so that the IP steam I104 is returned to the boiler 1 for reheating, thereby the Obtaining IP steam with an associated higher temperature and pressure is defined as IP steam II 105, the line of which will be in communication with the steam inlet of the IP steam turbine 3 for generating electricity.

As mentioned above, the boiler feedwater preheating system preferably includes a condenser 5, a first preheater 6, a degasser 7 and a second preheater 8, as shown in FIG. 1 . Wherein, the condenser 5 is used to mix the condensed water D and the waste steam 109 to obtain the boiler feed water I;

The first preheater 6 is for heating boiler feed water I to obtain boiler feed water II by heat exchange with steam from the LP steam turbine 4;

The degasser 7 is for heating boiler feed water II to obtain boiler feed water III by heat exchange with the steam from the IP steam turbine 3;

Said second preheater 8 is for heating boiler feed water III to obtain boiler feed water IV by heat exchange with steam from IP steam turbine 3 and HP steam turbine 2;

The line of the boiler feed water IV will be in communication with the boiler to circulate the boiler feed water IV to the boiler 1 for steam generation. In this case, the line of condensed water D and the line of waste steam 109 will communicate with the inlet of said condenser 5, and the water outlet of said condenser 5 will communicate with the water inlet of first preheater 6, said The water outlet of the first preheater 6 will communicate with the water inlet of the deaerator 7, the water outlet of the deaerator 7 will communicate with the water inlet of the second preheater 8, the second The water outlet of the preheater 8 will communicate with the water inlet of the boiler 1 .

As mentioned above, preferably, the boiler feed water preheating system further includes a line connecting the degasser 7 and the second preheater 8 so that the water extracted from the second preheater 8 and the boiler The steam after heat exchange of feed water III is sent to the deaerator 7 together with the steam extracted from the IP steam turbine 3 and is heat exchanged with the boiler feed water II in the deaerator 7 to obtain boiler feed water III .

As mentioned above, preferably, the boiler feed water preheating system further includes a pipeline connecting the first preheater 6 and the deaerator 7 so that the water extracted from the deaerator 7 passes through the boiler feed water II. The heat-exchanged steam is sent to the first preheater 6 together with the steam extracted from the LP steam turbine 4 and is heat-exchanged with the boiler feed water 1 in the first preheater 6 to obtain Boiler Feed Water II.

As mentioned above, preferably, the boiler feed water preheating system further includes a pipeline connecting the first preheater 6 and the condenser 5 so that the water extracted from the first preheater 6 and the The steam after the heat exchange of the boiler feed water I is sent to the condenser 5 to be mixed with the condensed water D and the waste steam 109 to obtain the boiler feed water I.

According to the present invention, preferably, as shown in FIG. 1 , the TES system includes a first storage tank 11 , a heat exchanger 12 and a second storage tank 13 . In this case, the first storage tank 11 is in communication with the boiler feedwater preheating system to store part of the boiler feedwater drawn from the boiler feedwater preheating system as a heat source during low load conditions;

The heat exchanger 12 is used to allow part of the heat source in the first storage tank 11 to exchange heat as a first stream 119 with a third stream 120 from the second storage tank 13 during high load conditions. The first stream 119 will form a second stream 123 after exchanging heat energy, and the third stream 120 will form a fourth stream 121 after heat exchanging absorbing heat energy;

A fourth stream 121 will be piped to the _CO2 capture system to provide thermal energy for absorbent regeneration during high load conditions while forming a condensate stream 122 back into the second storage tank 13;

The line of the second stream 123 communicates with the first storage tank 11 so as to return the second stream 123 to the first storage tank 11 .

According to the present invention, in order to save water and increase the mass flow of the recycled boiler feed water, preferably, the water flowing out of the first storage tank 11 is defined as the fifth stream 124 and the pipeline communicates with the water inlet of the condenser 5 so that The fifth stream 124 is mixed with condensate D and waste steam 109 . Wherein, the pipeline of the condensed water D and the pipeline of the waste steam 109 can be directly communicated with the condenser 5 to be combined therein, or as shown in FIG. The combined water of the waste steam 109 and the condensed water D, and then the pipeline of the combined water is communicated with the water inlet of the condenser 5 again.

According to the present invention, in order to save water and increase the mass flow of recycled boiler feed water, preferably, the deaerator 7, the line of the boiler feed water III, the second preheater 8, the line of the boiler feed water IV, or any combination of them.

Preferably, the boiler feedwater preheating system includes a deaerator, and the deaerator is in communication with the TES system such that the TES system is filled with a portion of the boiler feedwater drawn in part from the deaerator. Specifically, the boiler feedwater preheating system includes a line connecting the TES system and the degasser 7 to send only a portion of the boiler feedwater in the degasser 7 as the sixth stream 118 to the TES system during the low load stage as the sixth stream 118. Heat source to store thermal energy.

According to the present invention, the _CO2 capture system generally comprises a _CO2 absorber 9 and a _CO2 regenerator 10, as shown in Figure 1, in this case:

The _CO2 absorber 9: for absorbing CO2 in the flue gas 113 from the boiler 1 and obtaining a _CO2 -lean flue gas 114 and a _{CO2 -} rich absorbent 115;

The line of the _CO2 -rich absorbent 115 communicates with the absorbent inlet of the _CO2 regenerator 10 so that the _CO2 -rich absorbent 115 enters the _CO2 regenerator 10 for regeneration and obtains a _CO2 -lean absorbent 117 and desorption of CO ₂ 116;

The line of the lean CO ₂ absorbent 117 communicates with the absorbent inlet of the CO ₂ absorber 9 to recycle the lean CO ₂ absorbent 117 .

Wherein, the CO ₂ absorber 9 is provided with an outlet for discharging CO ₂ lean flue gas 114 , and the CO ₂ regenerator 10 is provided with an outlet for discharging and desorbed CO ₂ 116 .

As mentioned above, the thermal energy provided to the _CO2 capture system will be substantially provided to the _CO2 regenerator 10 to regenerate the absorbent so that the TES system and the lines of the second LP steam 107 will be connected to the CO2 regenerator 10. ₂ A regenerator 10 is connected to provide it with thermal energy.

The present invention will be described in detail below by means of examples.

In the following example:

The power station shown in the figure includes: a boiler 1, a steam turbine unit equipped with a boiler feedwater preheating system, a _CO2 capture system and a TES system; wherein the steam turbine unit includes an HP steam turbine 2, an IP steam turbine 3 and LP steam turbine 4; the boiler feed water preheating system includes a condenser 5, a first preheater 6, a degasser 7 and a second preheater 8; the TES system includes a first storage tank 11, a heat exchange 12 and a second storage tank 13; the CO ₂ capture system includes a CO ₂ absorber 9 and a CO ₂ regenerator 10 containing solvent MEA as a CO ₂ absorbent; the connection relationship of these devices is shown in FIG. 1 .

The power station shown in Fig. 2 is identically equipped with the power station shown in Fig. 1, except that the power station shown in Fig. 2 does not include a TES system.

Example 1

This example serves to illustrate the method and power plant of the present invention.

Using the power station shown in FIG. 1, specifically, the carbonaceous fuel 102 (pulverized coal) is sent to the boiler 1 for combustion to generate heat energy and flue gas 113, and the raw water 101 (composed of boiler feed water IV) is sent to the boiler at the same time 1 utilizes the thermal energy generated by the combustion of the carbonaceous fuel 102 to generate HP steam 103;

Send this HP steam 103 to HP steam turbine 2 to generate electricity and obtain IP steam I104, return this IP steam I104 to boiler 1 for reheating and obtain IP steam II 105;

Sending this IP steam II 105 to IP steam turbine 3 to generate electricity and obtain LP steam 106;

Part of the LP steam 106 is defined as the first LP steam 108 sent to the LP steam turbine 4 to generate electricity and obtain waste steam 109; the remaining part of the LP steam 106 is defined as the second LP steam 107 sent to the CO ₂ regenerator 10 Exchange heat with _CO2 -rich absorbent and form condensate D;

The waste steam 109 is first combined with the condensed water D, and the combined stream is sent to the condenser 5; the boiler feed water flowing out of the condenser 5 is defined as the boiler feed water I and sent to the first preheater 6 to be extracted from the LP. The steam of the steam turbine 4 is heated by heat exchange; the boiler feed water flowing out from the first preheater 6 is defined as boiler feed water II and sent to the deaerator 7 for heat exchange with the steam extracted from the IP steam turbine 3 to be heated. is heated and degassed therein; the boiler feed water from the degasser 7 is defined as boiler feed water III and sent to the second preheater 8 to be combined with the steam extracted from the IP steam turbine 3 and the HP steam turbine 2 The boiler feed water flowing out from the second preheater 8 is defined as boiler feed water IV and circulated back to the boiler 1 to be used as raw water 101;

Wherein, the steam extracted from the second preheater 8 and after heat exchange with the boiler feed water III is sent to the deaerator 7 together with the steam extracted from the IP steam turbine 3 and stored in the deaerator 7 Heat exchange is performed with boiler feed water II in the degasser 7 to obtain boiler feed water III; the steam extracted from the degasser 7 and subjected to heat exchange with the boiler feed water II is combined with the steam extracted from the LP The steam of the turbine 4 is sent together into the first preheater 6 and is heat exchanged with the boiler feed water I in the first preheater 6 to obtain boiler feed water II; will be extracted from the first preheater 6 The steam from the preheater 6 and after heat exchange with the boiler feed water I is sent to the condenser 5 to be mixed with the condensed water D and the waste steam 109 to obtain boiler feed water I.

During low-load operation, part of the boiler feed water in the degasser 7 is defined as the sixth stream 118 and sent to the first storage tank 11 for storage as a heat source;

During high load operation, a portion of the water in the first storage tank 11 is defined as the first stream 119 to be sent to the heat exchanger 12 for heat exchange with the third stream 120 from the second storage tank 13; and the first stream 119 will return to the first storage tank 11 a second stream 123 formed after the exchange of heat energy is released, and the third stream 120 will be returned to the first storage tank 11 to form a fourth stream 121 after the heat exchange has absorbed heat energy; the fourth stream 121 will be sent to CO ₂ The regenerator 10 exchanges heat with the _CO2 -rich absorbent and forms a condensate stream 122 that is returned to the second storage tank 13; wherein part of the water in the first storage tank 11 is defined as a fifth stream 124 that will be sent to the condenser 5 To participate in the formation of boiler feed water I;

Flue gas 113 will be sent to _CO2 absorber 9 containing solvent MEA to absorb CO2 in flue gas 113 and obtain _CO2 lean flue gas 114 (discharged from _CO2 absorber ₉ ) and _CO2 rich absorbent 115;

The _CO2 -rich absorbent 115 is sent to the _CO2 regenerator 10 for absorbent regeneration using the thermal energy provided above and the _CO2 -lean absorbent 117 is obtained to be recycled to the _CO2 absorber 9 to continue to utilize and desorb _CO2 (from _CO2 regenerator 10 discharge).

During the course of the day, the power station will operate at high load conditions for about 12 hours during the day and at low load conditions for about 12 hours at night; the high load conditions refer to the need for the steam turbine units to operate at higher than 75% rated Conditions for operation at capacity, said low load conditions refer to conditions that require the steam turbine unit to operate at less than 75% of its rated capacity.

Among them, the sixth stream 118 (up to 80 wt% of the total boiler feed water in the degasser 7) drawn from the degasser 7 is sent to the first storage tank 11 during the operation of the power station under low load conditions ; all thermal energy for regenerating the absorbent in the _CO2 regenerator 10 is provided by the second LP steam 107; this second LP steam 107 accounts for 21 wt% of the total LP steam 106; when the power station is operating under high load conditions During this period, boiler feedwater is not drawn from the boiler feedwater preheating system to the TES system; however, the boiler feedwater stored in the TES system during operation under low load conditions is released to regenerate the absorbent during this high load operation; ₂ The thermal energy for regenerating the absorbent in the regenerator 10 consists of 90% of the thermal energy provided by the TES system and 10% of the thermal energy provided by the second LP steam 107; this second LP steam 107 accounts for 3 wt% of the total LP steam 106 .

The result: when the power station is operating under high load conditions, HP steam turbine 2 can operate at 100% rated capacity, IP steam turbine 3 can operate at 95% rated capacity, and LP steam turbine can operate at 90% rated capacity capacity, so that the power station will generate more power as needed during periods of high load operation.

Comparative Example 1

This example uses the power plant shown in FIG. 2 that does not include a TES system, and the operation of this example is the same as that of Example 1, except that the thermal energy used to regenerate the absorbent in the CO ₂ regenerator 10 is entirely composed of LP steam provided (the second LP steam 107 is 28 wt% of the total LP steam 106 when the generator is operating under high load conditions), and all boiler feed water will be recycled to boiler 1 and not pumped to the TES system .

The result: When the power station is operating under high load conditions, HP steam turbine 2 can operate at 100% rated capacity, IP steam turbine 3 can operate at 80% rated capacity, and LP steam turbine can operate at 65% rated capacity capacity, so that the power station will not be able to generate as much power as it needs during periods of high load operation.

The preferred embodiments of the present invention have been described above in detail, however, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, a variety of simple modifications can be made to the technical solutions of the present invention, including combining various technical features in any other suitable manner. These simple modifications and combinations should also be regarded as the content disclosed in the present invention. All belong to the protection scope of the present invention.

Claims (10)

1. a kind of method from the power station run under the loading condiction of variation production electric power, which is characterized in that the power generation Stand including boiler, be equipped with steam turbine unit, the CO of boiler feedwater pre-heating system₂Trapping system and thermal energy storage (TES) System,

Wherein, it this method comprises: when the power station is run under low loading conditions, is extracted from the boiler feedwater pre-heating system Part boiler feedwater makes the CO to store into TES system₂The thermal energy portion that absorbent regeneration in trapping system uses Divide or all by being provided from the boiler feedwater being stored in the TES system.

2. according to the method described in claim 1, wherein, the CO₂Trapping system absorbs CO as absorbent using solvent₂。

3. method according to claim 1 or 2, wherein the steam turbine unit includes high pressure (HP) steamturbine Machine, middle pressure (IP) steam turbine and low pressure (LP) steam turbine, wherein taken out under low loading conditions from IP/LP intersection Take LP steam for the CO₂Absorbent regeneration in trapping system provides thermal energy, and for described under high-load condition CO₂The thermal energy of absorbent regeneration includes the thermal energy being stored in TES system in trapping system.

4. according to the method described in claim 3, wherein, being based under high-load condition in the CO₂In trapping system again The total heat energy of raw absorbent, is at least 25% by the thermal energy ratio for absorbent regeneration that the TES system provides, preferably At least 50%.

5. method described in any one of -4 according to claim 1, wherein the boiler feedwater pre-heating system includes degassing Device, and this method include from extraction section boiler feedwater in the degasser into the TES system to save as heat source；

It is preferably based on the total amount of the boiler feedwater in the degasser, extracted from the degasser and is sent to the TES system In boiler feedwater amount be 1-90 weight %, preferably 10-85 weight %.

6. method described in any one of -5 according to claim 1, wherein the power station is coal-fired rankine cycle or natural Gas combined cycle.

7. a kind of with CO₂The power station of trapping system, which is characterized in that the power station includes: boiler, to be equipped with boiler feedwater pre- Steam turbine unit, the CO of hot systems₂Trapping system and thermal energy storage (TES) system；

Wherein, TES system and the boiler feedwater pre-heating system and CO₂Trapping system is connected, so that the power station is low negative When being run under the conditions of lotus, from the boiler feedwater pre-heating system extraction section boiler feedwater to store into TES system, and make The CO₂The thermal energy that absorbent regeneration in trapping system uses is partly or entirely by from being stored in the TES system Boiler feedwater provides.

8. power station according to claim 7, wherein the steam turbine unit includes high pressure (HP) steamturbine Machine, middle pressure (IP) steam turbine and low pressure (LP) steam turbine, and IP/LP intersection and the CO₂Trapping system phase Even, so that extracting LP steam from the IP/LP intersection under low loading conditions as the CO₂Absorbent in trapping system Regeneration provides thermal energy.

9. power station according to claim 7 or 8, wherein the boiler feedwater pre-heating system includes degasser, and described Degasser is connected to the TES system, so that the TES system is drawn from the part boiler of the degasser filled with part Water supply.

10. the power station according to any one of claim 7-9, wherein the power station be coal-fired rankine cycle or Gas theory.