JP5584040B2 - CO2 recovery steam turbine system and operation method thereof - Google Patents

Description

  The present invention relates to a carbon dioxide recovery steam turbine system that separates and recovers carbon dioxide from generated exhaust gas and the like, and an operation method thereof.

  Due to the rapid increase in consumption of fossil resources, the atmospheric carbon dioxide concentration, which was 280 ppm before the Industrial Revolution, has increased to about 380 ppm in recent years. Recent studies have shown that this increase in carbon dioxide concentration is likely to be a major factor in global warming that has become apparent in recent years. To address this issue, countries are working to reduce greenhouse gas emissions in accordance with the Kyoto Protocol to the United Nations Framework Convention on Climate Change.

  Under such circumstances, in a thermal power plant using a large amount of fossil fuel, an iron manufacturing plant, or the like, a method for separating and recovering carbon dioxide by contacting exhaust gas with an amine-based absorbent has been studied. As a system for realizing this, an absorption tower that absorbs carbon dioxide contained in exhaust gas and an absorption liquid (rich liquid) after absorption of carbon dioxide supplied from the absorption tower are heated, and carbon dioxide from the rich liquid is heated. A carbon dioxide recovery device is known that includes a regeneration tower that releases gas and regenerates an absorbing solution (see, for example, Patent Document 1). A reboiler as a heat source is connected to the regeneration tower. The absorption liquid (lean liquid) regenerated in the regeneration tower is supplied to the absorption tower, and the absorption liquid circulates in this system. For example, in a power generation system including a steam turbine, a large part of the latent heat of condensation can be used, and thus a part of the steam circulating in the system is typically supplied to the reboiler. For example, Non-Patent Document 1 discusses the steam extraction point. In this non-patent document 1, an example of extracting from the exhaust of an intermediate pressure turbine is shown. However, since this extraction pressure is generally higher than the pressure of the steam supplied to the reboiler, a method of recovering energy by a back pressure turbine installed in the front stage of the reboiler has been studied. This extraction from the exhaust of the medium pressure turbine can have a relatively small effect on the turbine performance rather than extracting from the middle of the low pressure turbine, especially when the amount of extracted steam is large. Is widely known as an applicable technique.

  However, in a system using such a back pressure turbine, for example, in the case of 100% load operation, the steam pressure supplied to the reboiler is fixed by the amount of extracted steam. For this reason, when trying to apply a new absorbing liquid having a different regeneration temperature and amount of steam used from the conventional one, there is a problem that the supplied steam pressure and saturation temperature may differ from the required steam properties. is there. If the supplied steam pressure is lower than the required pressure, there is of course a problem. However, in the reverse case, it is necessary to reduce the pressure via a valve or the like. In this case, the pressure is unnecessarily lowered without recovering energy.

JP 2005-254212 JP

RITE carbon dioxide fixation, effective utilization technology countermeasure project H18 result report (Part III Chapter 3)

  The present invention has been made in consideration of the above circumstances, and can be applied to various absorption liquids and carbon dioxide recovery devices, and can flexibly cope with load fluctuation operation, and is a carbon dioxide recovery type steam. It is an object of the present invention to provide a turbine system and an operation method thereof.

  A carbon dioxide recovery steam turbine system according to a first aspect of the present invention includes a steam generating device, a steam turbine device having a plurality of steam turbines driven by steam generated from the boiler, and exhausted from the boiler. Carbon dioxide is separated and recovered from the carbon dioxide-containing exhaust gas, and a carbon dioxide recovery device including a reboiler for heating the absorption liquid is provided upstream of the carbon dioxide recovery device, and the exhaust of the steam turbine device is supplied, A first back pressure turbine that supplies exhaust steam to the reboiler and has a plurality of exhaust passages, and a first pressure adjustment unit that adjusts the pressure of the exhaust of the first back pressure turbine. Features.

  The carbon dioxide recovery steam turbine system according to the second aspect of the present invention is a steam including a boiler that generates steam, a high-pressure turbine that is driven by the steam generated from the boiler, an intermediate-pressure turbine, and a low-pressure turbine. A turbine apparatus, and a carbon dioxide recovery apparatus including a reboiler for heating an absorption liquid that separates and recovers carbon dioxide from a carbon dioxide-containing exhaust gas discharged from the boiler, and operates by being supplied with a part of the exhaust of the intermediate pressure turbine; A first back having a plurality of exhaust passages provided between the intermediate-pressure turbine and the low-pressure turbine, wherein a part of the exhaust of the intermediate-pressure turbine flows in and the exhaust gas flowing out to the low-pressure turbine is supplied. A pressure turbine; and a first pressure adjusting unit that adjusts an exhaust pressure of the first back-pressure turbine.

  According to the present invention, it can be applied to various absorbents and carbon dioxide recovery devices, and can flexibly cope with load fluctuation operation.

1 is a block diagram showing a carbon dioxide recovery steam turbine system according to a first embodiment. The figure which shows the 1st specific example of the back pressure turbine used for the carbon dioxide recovery type | mold steam turbine system by 1st Embodiment. The figure which shows the 2nd specific example of the back pressure turbine used for the carbon dioxide recovery type | mold steam turbine system by 1st Embodiment. The figure which shows the back pressure turbine by a comparative example. The figure which shows one specific example of the carbon dioxide recovery apparatus used for the carbon dioxide recovery type steam turbine system by 1st Embodiment. A block diagram showing a carbon dioxide recovery type steam turbine system by a 2nd embodiment. A block diagram showing a carbon dioxide recovery type steam turbine system by a 3rd embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. Moreover, in FIG. 1 thru | or FIG. 7, the thing with the same code | symbol has shown the same thing, and the overlapping description is abbreviate | omitted.

(First embodiment)
FIG. 1 shows a carbon dioxide recovery steam turbine system (hereinafter also referred to as a steam turbine system) according to a first embodiment of the present invention. In the present embodiment, a carbon dioxide recovery steam turbine system mainly used in a coal-fired power plant that burns pulverized coal is shown, but the present invention is not limited to this, and is applicable to, for example, a combined cycle of natural gas or the like.

  The steam turbine system 1 of the present embodiment includes a boiler 11, a high pressure turbine 13, an intermediate pressure turbine 15, a low pressure turbine 17, a generator 19, a condenser 21, a back pressure turbine 23, and carbon dioxide recovery. The apparatus 30 and the pumps 41 and 43 are provided. The high-pressure turbine 13, the intermediate-pressure turbine 15, and the low-pressure turbine 17 are connected in tandem to form a steam turbine device, and the generator 19 is driven by the steam turbine device. Note that these are not necessarily tandem. For example, only the high-pressure turbine 13 and the medium-pressure turbine 15 may be coaxial, and the low-pressure turbine 17 may be a separate axis.

  The steam that is heated and vaporized in the boiler 11 drives the high-pressure turbine 13 and then reheats in the boiler 11 and then drives the intermediate-pressure turbine 15. A part of the exhaust from the intermediate pressure turbine 15 is sent to the low pressure turbine 17, and the remaining exhaust from the intermediate pressure turbine 15 is supplied to the back pressure turbine 23 to drive the back pressure turbine 23. Although not shown in FIG. 1, the back pressure turbine 23 can be coupled with a generator or a compressor for compressing the recovered carbon dioxide.

  A part of the exhaust gas from the intermediate pressure turbine 15 sent to the low pressure turbine 17 is condensed by the condenser 21 after driving the low pressure turbine 17. The condensed steam is supplied again to the boiler 11 via the pump 41. The exhaust gas 12 from the boiler 11 is sent to the carbon dioxide recovery device 30, and oxygen dioxide in the exhaust gas 12 from the boiler 11 is separated and recovered by the carbon dioxide recovery device 30 as described later.

  A plurality of exhaust passages 24 a and 24 b are provided on the exhaust side of the back pressure turbine 23. The exhaust position from the back pressure turbine 23, that is, the exhaust pressure can be made variable by adjustment by the pressure adjusting unit. For example, as shown in FIG. 2, the back pressure turbine 23 has a plurality of back pressure turbine elements 23 a and 23 b installed on the same axis, and two exhaust passages 24 a and 24 b are provided on each exhaust side. If provided, a switching valve 25a is provided at the tip of the exhaust flow path 24a, and the exhaust pressure from the back pressure turbine 23 can be varied by switching the open / close state of the switching valve 25a. The exhaust passages 24 a and 24 b are configured to be one and serve as a passage for the carbon dioxide recovery device 30. That is, the switching valves 25a and 25b constitute a pressure adjusting unit. In this example, the case where there are two back-pressure turbine elements is shown, but the number of turbine elements is not necessarily limited to this, and can be three or more. In this case, the exhaust pressure can be adjusted more finely.

  For example, as shown in FIG. 3, the back pressure turbine 23 has a plurality of back pressure turbine elements 23a and 23b installed on the same axis, and the rotary shaft is separated between the adjacent back pressure turbine elements 23a and 23b. Consider a case where a mechanism (hereinafter also referred to as a clutch) 231 is provided and the back pressure turbine element 23b is driven by the exhaust of the back pressure turbine element 23a. In this case, by providing the switching valve 25a on the inlet side of the back pressure turbine element 23b where the exhaust flow path 24a of the back pressure turbine element 23a is branched, and providing the switching valve 25b on the other side, the back pressure turbine is provided. The exhaust pressure from 23 can be made variable. In this case, for example, when the steam is exhausted from the exhaust passage 24a, the clutch 231 is disengaged in addition to the operation of the switching valve 25a, so that it is not necessary to rotate the back pressure turbine element 23b. Need not be supplied. Also in FIG. 3, the exhaust flow paths 24 a and 24 b are configured to be a single flow path for the carbon dioxide recovery device 30. Also in the case shown in FIG. 3, the switching valves 25a and 25b constitute a pressure adjusting unit. In this case, the number of back pressure turbine elements can be three or more, as in the case shown in FIG.

  Conventionally, the exhaust from the back pressure turbine is saturated with steam if necessary, and then supplied to the reboiler of the carbon dioxide recovery device. In this case, for example, when the amount of steam used in the carbon dioxide recovery device 30 is smaller than that in the conventional case, the amount of steam passing through the low-pressure turbine increases and the outlet pressure of the intermediate-pressure turbine increases. For this reason, when the back pressure turbine 230 having only one exhaust flow path 240 is used as in the comparative example shown in FIG. The outlet pressure increases, and depending on the properties of the absorbing liquid, the optimum steam temperature necessary for regeneration and the actual supply steam temperature may deviate.

  On the other hand, in the case of a steam turbine system in which the exhaust pressure of the back pressure turbine can be changed as shown in FIG. 2 or FIG. 3, for example, the exhaust outlet of the back pressure turbine 23 is connected to the exhaust flow, for example. By changing from the passage 24a to the exhaust passage 24b, the outlet pressure of the back pressure turbine 23 can be lowered. Such a steam turbine system also makes it possible to adjust the outlet pressure of the back pressure turbine 23 in the vicinity of a desired value during partial load operation. In addition, in order to assist the control of pressure and flow rate, adjustment by a known valve can be used together in this embodiment. Even in this case, the loss in the valve can be reduced as compared with the case where the control is performed only by the valve.

  Next, a specific example of the carbon dioxide recovery device 30 used in the steam turbine system of this embodiment will be described with reference to FIG. The carbon dioxide recovery device 30 of this specific example includes a gas-liquid separator 302, an absorption tower 306, a gas cooler 308, a heat exchanger 312, a reboiler 320, a regeneration tower 322, a gas cooler 324, A gas-liquid separator 326.

  The exhaust gas from the boiler 11 is introduced into the lower part of the absorption tower 306 through the exhaust gas introduction line 12, while the lean liquid transferred from the regeneration tower 322 through the heat exchanger 312 and the lean liquid line 314, that is, regenerated, carbon dioxide. The absorption liquid having a reduced content is introduced into the absorption tower 306 and flows down through the absorption tower 306 filled with a filler for increasing the efficiency of gas-liquid contact. As the absorbing liquid, for example, a mixture of an amine compound and water is preferably used. Most of the carbon dioxide contained in the introduced exhaust gas is absorbed by the absorbent, and the treated exhaust gas is discharged from the top of the absorption tower 306. The discharged exhaust gas is cooled by a gas cooler 308 and separated into a gas and a condensed liquid by a gas-liquid separator 302. The liquid is supplied to an absorption tower 306 through an absorption tower reflux line 304, and the gas is supplied to a system through an exhaust gas outlet line 316. Released outside. In addition, since the amount of water in the circulation system gradually increases due to the water in the exhaust gas introduced into the absorption tower 306, it is possible to discharge a part of this refluxed liquid out of the system.

  The absorbing liquid that has absorbed carbon dioxide, that is, the rich liquid, discharged from the lower part of the absorption tower, is introduced into the heat exchanger 312 through the rich liquid line 310. In the heat exchanger 312, heat exchange is performed with the high-temperature lean liquid flowing out from the regeneration tower 322, the temperature is raised, and the heat is then introduced into the regeneration tower 322 and flows down inside the regeneration tower 322. Further, the absorption liquid at the bottom of the regeneration tower 322 circulated and supplied to the reboiler 320 exchanges heat with the steam supplied from the outside in the reboiler 320, thereby partially evaporating the lower part of the regeneration tower 322. While being introduced again, the absorption liquid is heated by condensation heat while rising in the regeneration tower 322, and reaction heat of carbon dioxide release reaction (endothermic reaction) is supplied. From the top of the regeneration tower 322, exhaust gas containing carbon dioxide is cooled by a gas cooler 324. The cooled exhaust gas is separated into a gas and a condensed liquid by a gas-liquid separator. The liquid is recovered to the regeneration tower 322 through the regeneration tower reflux line 328, and the gas, that is, carbon dioxide is recovered through the recovery carbon dioxide line 330. Is done. As described above, since the amount of water in the circulation system gradually increases due to the moisture in the exhaust gas introduced into the absorption tower 306, it is possible to discharge part of this refluxed liquid out of the system. The lean liquid flowing out from the regeneration tower 322 is cooled by the heat exchanger 312 described above, further cooled by a lean liquid cooler (not shown) if necessary, and introduced into the absorption tower 306.

  As described above, according to the present embodiment, the exhaust pressure of the back pressure turbine 23 can be adjusted. Therefore, the exhaust pressure can be applied to various absorption liquids and carbon dioxide recovery devices, and load fluctuation operation can be performed. It can respond flexibly.

(Second Embodiment)
Next, FIG. 6 shows a carbon dioxide recovery steam turbine system according to a second embodiment of the present invention. The steam turbine system 1A of this embodiment is the same as the steam turbine system 1 of the first embodiment shown in FIG. 1 except that a back pressure turbine 27 having a plurality of exhaust passages 28a and 28b is replaced with an intermediate pressure turbine 15 and a low pressure turbine 17. It is the structure newly provided in between. The back pressure turbine 27 can be the same as that shown in FIG. 2 or 3 described in the first embodiment. By providing the back pressure turbine 27, for example, even when a carbon dioxide recovery device is installed in an existing power plant, the outlet pressure of the intermediate pressure turbine is set to the medium pressure in the same manner as when the back pressure turbine 27 is not provided. The efficiency of the turbine 15 can be increased. Here, when the back pressure turbine 27 has the same configuration as that of the comparative example shown in FIG. 4, for example, when the amount of steam used in the carbon dioxide recovery device decreases due to the change of the absorbing liquid, etc., the intermediate pressure turbine As a result, the outlet pressure of 15 increases, and the efficiency of the intermediate pressure turbine 15 decreases.

  On the other hand, when using a back pressure turbine capable of making the exhaust position (exhaust pressure) variable as shown in FIG. 2 or 3 as the back pressure turbine 27 as in the present embodiment, for example, By changing the exhaust outlet of the back pressure turbine 27 from the exhaust passage 28b to the exhaust passage 28a, the outlet pressure of the intermediate pressure turbine 15 can be lowered to near the design point. In this case, the outlet pressure of the back pressure turbine 23 becomes larger than the case where the back pressure turbine 27 is not used in the conventional steam amount used in the carbon dioxide recovery device, but this is newly absorbed by changing the exhaust position. It is possible to adjust to a pressure suitable for the liquid. Such a steam turbine system also makes it possible to adjust the outlet pressure of the intermediate pressure turbine and the outlet pressure of the back pressure turbine 23 to a desired value in the partial load operation.

  As described above, according to the present embodiment, the exhaust pressure of the back pressure turbines 23 and 27 can be adjusted. Therefore, the exhaust pressure can be applied to various absorption liquids and carbon dioxide recovery devices, and the load It can flexibly handle variable operation.

(Third embodiment)
Next, a carbon dioxide recovery steam turbine system according to a third embodiment of the present invention is shown in FIG. The steam turbine system 1B of the present embodiment is the same as the steam turbine system 1A of the second embodiment shown in FIG. 6 except that the back pressure turbine 23 is deleted and a part of the exhaust of the intermediate pressure turbine 15 is directly sent to the carbon dioxide recovery device 30. It is a supplied configuration.

  In the steam turbine system of the present embodiment configured as described above, when the outlet pressure of the intermediate pressure turbine 15 is not so different from the pressure of the steam supplied to the reboiler, a part of the exhaust of the intermediate pressure turbine 15 is directly used. It is possible to supply to the carbon dioxide recovery device 30.

  Since this third embodiment can also adjust the exhaust pressure of the back pressure turbine 27, it can be applied to various absorbing liquids and carbon dioxide recovery devices, and can flexibly cope with load fluctuation operation. be able to.

  The present invention has been specifically described above based on the embodiments. However, the present invention is not limited to these descriptions. As long as the above-described embodiments are appropriately modified by those skilled in the art, they are also included in the scope of the present invention as long as they have the characteristics of the present invention. For example, the elements included in the embodiment of the present invention and the arrangement thereof are not limited to those illustrated, and can be appropriately changed.

  Further, combinations can be made as long as technically possible, and combinations thereof are also included in the scope of the present invention as long as they include the features of the present invention.

DESCRIPTION OF SYMBOLS 1 Carbon dioxide recovery type steam turbine system 1A Carbon dioxide recovery type steam turbine system 1B Carbon dioxide recovery type steam turbine system 11 Boiler 13 High pressure turbine 15 Medium pressure turbine 17 Low pressure turbine 19 Generator 21 Condenser 23 Back pressure turbine 27 Back pressure Turbine 23a Back pressure turbine element 23b Back pressure turbine element 24a Exhaust flow path 24b Exhaust flow path 25a Switching valve 25b Switching valve 26 Steam supplied to carbon dioxide recovery device 30 Carbon dioxide recovery device 32 Drain water 41 of carbon dioxide recovery device Pump 43 Pump 231 clutch

Claims (7)

A boiler that generates steam;
A steam turbine device having a plurality of steam turbines driven by steam generated from the boiler;
A carbon dioxide recovery device that separates and recovers carbon dioxide from the carbon dioxide-containing exhaust gas discharged from the boiler, and includes a reboiler for heating the absorption liquid;
A plurality of back pressure turbine elements connected in series are provided upstream of the carbon dioxide recovery device, and the exhaust of the steam turbine device flows into the first back pressure turbine element of the plurality of back pressure turbine elements. has a plurality of exhaust flow passages at least a portion of the exhaust gas is branched to flow into the back-pressure turbine element in the subsequent stage of the previous back-pressure turbine element, first back supplying exhaust steam to the reboiler A pressure turbine,
A first pressure adjusting unit that adjusts an exhaust pressure of the first back pressure turbine by switching at least one of the plurality of exhaust passages ;
Carbon dioxide capture steam turbine system that features. The steam turbine system includes a high pressure turbine, a medium pressure turbine and a low pressure turbine, part of the exhaust gas of the intermediate pressure turbine is carbon dioxide recovery according to claim 1, wherein that will be supplied to the first back-pressure turbine Type steam turbine system. A plurality of back-pressure turbine elements installed in series and connected between the intermediate-pressure turbine and the low-pressure turbine, and a part of the exhaust of the intermediate-pressure turbine is a first stage of the plurality of back-pressure turbine elements It flows into the back-pressure turbine element having a plurality of exhaust flow path branched so that at least a portion of the exhaust of the preceding back-pressure turbine component flows into the back-pressure turbine elements of a subsequent stage, the low-pressure exhaust flowing out a second back-pressure turbine is supplied to the turbine,
A second pressure adjusting unit that adjusts an exhaust pressure of the second back pressure turbine by switching at least one of the plurality of exhaust passages ;
Carbon dioxide capture steam turbine system according to claim 2, wherein that features. A boiler that generates steam;
A steam turbine apparatus including a high-pressure turbine, an intermediate-pressure turbine, and a low-pressure turbine driven by steam generated from the boiler;
A carbon dioxide recovery device including a reboiler for heating an absorbing liquid that separates and recovers carbon dioxide from a carbon dioxide-containing exhaust gas discharged from the boiler, and operates by being supplied with a part of the exhaust of the intermediate pressure turbine;
A plurality of back-pressure turbine elements provided between the intermediate-pressure turbine and the low-pressure turbine and connected in series are provided, and a part of the exhaust of the intermediate-pressure turbine is a first stage of the plurality of back-pressure turbine elements. A plurality of exhaust passages branched into the back pressure turbine element so that at least a part of the exhaust of the back pressure turbine element at the front stage flows into the back pressure turbine element at the back stage; a first back-pressure turbine is supplied to the turbine,
A first pressure adjusting unit that adjusts an exhaust pressure of the first back pressure turbine by switching at least one of the plurality of exhaust passages ;
Carbon dioxide capture steam turbine system that features. Each of the plurality of back-pressure turbine element of the first back-pressure turbine or the second back-pressure turbine is connected coaxially via a disconnecting mechanism of the rotary shaft, the first pressure regulator or the second carbon dioxide capture steam turbine system of operation of the pressure adjustment unit according to any preceding claim you conjunction with the operation of the disconnecting mechanism 1-4. Steam is generated in the boiler,
A steam turbine is driven by the steam generated from the boiler,
Back pressure comprising a plurality of back-pressure turbine elements connected in series, and a plurality of exhaust passages branched such that at least a part of the exhaust of the front-stage back-pressure turbine element flows into the back-pressure turbine element of the rear stage The steam turbine exhaust is supplied to the first-stage back pressure turbine element of the turbine,
Separating and recovering carbon dioxide from exhaust steam supplied from the back pressure turbine and carbon dioxide-containing exhaust gas discharged from the boiler;
Wherein the plurality of exhaust passages at least the back pressure method for operating a carbon dioxide capture steam turbine system that adjusts the pressure of the exhaust gas turbine by one to switch the. Steam is generated in the boiler,
A high pressure turbine, an intermediate pressure turbine, and a low pressure turbine are driven by the steam generated from the boiler,
Back pressure comprising a plurality of back-pressure turbine elements connected in series, and a plurality of exhaust passages branched such that at least a part of the exhaust of the front-stage back-pressure turbine element flows into the back-pressure turbine element of the rear stage A portion of the exhaust from the intermediate pressure turbine is supplied to the first back pressure turbine element of the turbine ,
Exhaust gas from the back pressure turbine is supplied to the low pressure turbine,
Separating and recovering carbon dioxide from part of the exhaust of the intermediate pressure turbine and carbon dioxide-containing exhaust gas discharged from the boiler;
Wherein the plurality of exhaust passages at least the back pressure method for operating a carbon dioxide capture steam turbine system that adjusts the pressure of the exhaust gas turbine by one to switch the.

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