JP2013241934A - High-temperature steam turbine power plant for performing double reheating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide USC steam power plant improved double reheat which are both, technically and economically, better suited for commercially viable installations.SOLUTION: A first intermediate pressure turbine 161 has a steam outlet 125 connected in operation to a second steam reheater 152, a second intermediate pressure turbine 162 has a steam inlet 126 for receiving steam from the second steam reheater 152 and a steam outlet 127 connected to a low pressure turbine 163, the intermediate pressure turbines are respectively separated into high temperature turbines 161-1 and 161-2 and low temperature turbines 161-2 and 162-2, and the high temperature turbine 161-1 of the first intermediate pressure turbine 161 and the high temperature turbine 162-1 of the second intermediate pressure turbine 162 are joined to a separate steam inlet 128 and an outlet pipe 125 of the first intermediate pressure turbine 161 and a separate steam inlet 129 and an outlet pipe 127 for the high temperature turbine 162-1 of the second intermediate pressure turbine 162.

Description

FIELD OF THE INVENTION The present invention relates to a high temperature steam turbine power plant with double reheating that is driven by a main or live steam temperature of 650 ° C. or higher in the first and second reheating and has a power output of 100 MW or higher. .

BACKGROUND OF THE INVENTION Steam power plants currently in operation have a main steam temperature of up to about 600 ° C. When operating at or near this temperature, power plants are commonly referred to as “supercritical” because the main steam pressure will be higher than the critical pressure. Efforts to increase the efficiency of supercritical power plants by increasing steam temperature have been greatly hampered by the lack of suitable materials for boilers, turbines and feed pipes. Even conventional steels based on chromium lose their stability below 650 ° C.

  Power plants designed to break through the obstacles currently imposed by available materials are often referred to as ultra supercritical or USC steam plants. In order to obtain steam temperatures higher than 650 ° C, parts exposed to high temperatures require nickel-based alloys, which are expensive and forging into large forgings that exceed the 10-ton limit. It is difficult. This limitation may be insufficient for large steam turbine plant rotors, such as those described in published US Patent Application No. 2008/0250790.

  On the other hand, a method described as “double reheat” has been proposed and has been used for over 50 years, as evidenced, for example, by US Pat. No. 2,955,429. The dual reheat system has an additional return flow in the main steam path to the boiler or reheater. In a typical single reheat system, the return path returns the exit steam from the first or high pressure turbine to the boiler for preheating before re-entering the turbine stage at the second or medium pressure. In a dual reheat system, a similar return path exists at the outlet of the medium pressure turbine to reheat the steam before it enters the second (lower) medium or low pressure turbine stage. To do.

  Double reheat systems have been proposed as a means to further increase the efficiency of USC steam plants. For example, R. Blum, J. Bugge, S. Kjaer, “AD700 innovations pave the way for 53 per cent efficiency” in Modern Power Systems, November 2008, 15-19. Page.

R.Blum, J.Bugge, S.Kjaer, "AD700 innovations pave the way for 53 per cent efficiency" in Modern Power Systems, November 2008, 15-19

  However, the proposed double reheat system for USC steam power plants has not been fully optimized for the properties and costs of existing materials. Accordingly, it is an object of the present invention to provide an improved double reheat of a USC steam power plant that is technically and economically more suitable for commercially available equipment.

  According to one aspect of the present invention, a steam power plant, wherein at least one high pressure turbine or turbine section having a steam outlet connected to a first steam reheater during operation in one rotor; At least two intermediate pressure turbines or turbine sections, the first of the at least two intermediate pressure turbines or turbine sections having a steam outlet connected to the second steam reheater during operation. A second one of the at least two intermediate pressure turbines or turbine sections includes a steam inlet for receiving steam from the second steam reheater, and one or more low pressure turbines or turbine sections. A steam outlet connected to each other, wherein the at least two intermediate pressure turbines or turbine sections are each A high-temperature turbine or turbine section, is separated into a low-temperature turbine or turbine section, the steam power plant is provided.

  The hot turbine or turbine section can receive reheated steam at a temperature above 650 ° C, preferably above 700 ° C. This also makes the high temperature turbine or turbine section at least partially manufactured from modern materials such as nickel-based alloys.

  The four turbines or turbine sections resulting from the separation of the medium pressure turbine can preferably be recombined into a dual flow turbine, resulting in a dual flow hot turbine, a dual flow cold turbine, or both .

  These and other aspects of the invention will become apparent from the following detailed description or the drawings listed below.

  Exemplary embodiments of the invention will now be described with reference to the accompanying drawings.

It is a reproduction of a known ultra supercritical steam power plant design. It is a figure which shows the improvement by the 1st aspect of this invention. It is a figure which shows the 2nd aspect of this invention.

DETAILED DESCRIPTION OF THE INVENTION The plant design 10 of FIG. 1 shows a known USC steam plant with double reheat. In the steam generator or boiler 11, live steam is generated from a water return cycle (not shown) and guided to the first turbine 14 through the main steam supply pipe 121 and the main steam inlet valve 131. Turbine 14 is commonly referred to as a high pressure or HP turbine. The main steam path exits HP turbine 14 through tube 122. Tube 122 then branches to first reheater return tube 123. In the first reheater 151 in the general part of the boiler 11, the main steam flow is reheated and then enters the supply pipe 124 and passes through the inlet valve 132 to the first intermediate pressure or IP turbine. 161.

  At this stage, the feed steam has acquired a temperature close to or even higher than the original live steam temperature due to reheating. The first IP turbine 161 is basically manufactured using the same heat resistant material as that of the HP turbine 14. A return pipe 125 communicates with the second reheater 152 from the outlet of the first IP turbine 161.

  In the second reheater 152, the steam is again heated to a temperature close to or even higher than the original live steam temperature. After passing through the second reheater, the steam enters the steam supply pipe 126 and enters the second intermediate pressure turbine 162 through the valve 133. The second IP turbine 162 is also basically manufactured using the same heat-resistant material as the HP turbine 14 and the first IP turbine 161.

  The steam at the outlet of the second IP turbine 162 is guided to one or more low pressure or LP turbines 163 and finally expanded to a condensed state. The LP turbine 163 is configured as a so-called “double flow” turbine with two balanced branches in one inner casing.

  All turbines share a single rotor shaft 17 that drives an electromagnetic generator 18, as is known in the art.

  The plant design 10 of FIG. 2A shows a USC steam plant with double reheat, with a reheat system according to an embodiment of the present invention. The reference numerals of components that are basically equal or have similar functions are the same as those in FIG. In the design of FIG. 2A, a steam generator is also used to generate steam from a water return cycle (not shown) and guide the steam through the main steam supply pipe 121 and the main steam inlet valve 131 to the first turbine 14. Alternatively, a live steam boiler 11 is provided. As in the embodiment of FIG. 1, the turbine 14 is a high pressure or HP turbine formed from a material suitable for a temperature of about 700 ° C. and a main steam pressure P 0 of about 350 bar. As described above, the main steam path exits the HP steam turbine 14 through the pipe 122. Tube 122 then branches to first reheater return tube 123. In the first reheater 151, which is typically part of the boiler 11, the main steam flow is reheated and then enters the supply pipe 124 and passes through the inlet valve 132 to the first medium pressure or IP turbine 161. Pass through.

  The first intermediate pressure or IP turbine 161 is separated in this embodiment into a first hot portion 161-1 and a second cold portion 161-2. When referring to separation, it means that the first hot part 161-1 is housed in or surrounded by an inner casing separated from the inner casing of the second cold part 161-2. Means that. The first hot part 161-1 has a unique inner casing. When referring to the step of separating the first intermediate pressure or IP turbine 161 into a first hot part 161-1 and a second cold part 161-2, its most significant element is therefore to connect both parts of the turbine. , Housing in different inner casings (each with different supply and outlet lines).

  At this stage, the feed steam has acquired a temperature of about 720 ° C. and a pressure of about 75 bar by reheating. The first hot portion 161-1 of the IP turbine 161 is manufactured using essentially the same refractory material as the HP turbine 14, while lower pressure due to the reduced steam pressure from the first reheat cycle. Requires resistance. The supply pipe 128 connects the outlet of the high temperature portion 161-1 to the second low temperature portion 161-2.

  Since the second cold part 161-2 of the turbine 161 is no longer exposed to the same high temperature as the first part 161-1, the second cold part 161-2 is applied, for example, in the production of a steam turbine for supercritical steam. Can be manufactured using more common materials. The second cold section 161-2 of the turbine 161 is shown as a double flow turbine with two balanced branches in one inner casing. The outlet of the second cold section 161-2 is coupled to a return pipe 125 that returns steam to the second reheater 152.

  Separation of the first IP turbine 161 into the first hot part 161-1 and the second cold part 161-2 has the advantage of dividing the casing and turbine components only into the hot and cold components. There is no need to manufacture the entire IP turbine from high temperature components, nor is it necessary to weld one casing member or other turbine member formed from a high temperature alloy to the other, a common alloy. Welding between different alloys in a high temperature steam environment has been found to pose a risk of cracking and can be a major cause of long-term defects in USC turbine plants.

  In the second reheater 152, the steam is again heated to a temperature of about 720 or 730 ° C. After passing through the second reheater, the steam enters the steam supply pipe 126 and enters the second intermediate pressure turbine 162 through the valve 133. Like the first IP turbine 161, the second IP turbine 162 is also separated in this embodiment into a first hot portion 162-1 and a second cold portion 162-2. Separation means that the first hot part 162-1 is housed in or surrounded by an inner casing separated from the inner casing of the second cold part 162-2. The first hot portion 162-1 has its own inner casing.

  At this stage, the feed steam has acquired a temperature of about 720 or 730 ° C. and a pressure of about 30 bar by reheating. The first hot portion 162-1 of the IP turbine 162 is manufactured using essentially the same refractory material as the HP turbine 14 and the first hot portion 161-1 while from the second reheat cycle. The reduced vapor pressure requires a lower pressure resistance than the first hot portion 161-1. The supply pipe 129 connects the outlet of the high temperature portion 162-1 to the second low temperature portion 162-2.

  Since the second cold part 162-2 of the second IP turbine 162 is no longer exposed to the same high temperature as the first part 162-1, the second cold part 162-2 is for example for supercritical steam. It can be manufactured using more common materials as applied in the manufacture of steam turbines. The second cold section 162-2 of the turbine 162 is shown as a dual flow turbine with two balanced branches in one inner casing. The outlet of the second cold section 162-2 is coupled to a supply pipe 127, which supplies one or more low-pressure or LP turbines 163 to eventually expand the steam to a condensed state. Transport to. The LP turbine 163 is configured as a so-called “dual flow” turbine with two balanced branches in one inner casing. In an embodiment, a single dual-flow turbine 163 may be used as one, two, three, four, or five of such turbines, depending on the overall steam mass flow through the plant. , Representing any number of LP turbines.

  All turbines in FIG. 2A share a single rotor shaft 17 that drives an electromagnetic generator 18 as known in the art.

  The advantage gained by the plant aspect as shown in FIG. 2A is that the hot turbine sections 161-1 and 162-1 are coupled to a double flow casing 164 as shown in the embodiment of FIG. Further enhancement can be achieved by having dedicated supply and outlet tubes. In FIG. 2B, the reference numerals of components that are basically equal or have similar functions are the same as those in FIG. 2A.

  Thus, in FIG. 2B, the hot turbine portions 161-1 and 162-1 are shown coupled to a dual flow turbine casing 164. The supply pipe 124 supplies the steam from the first reheater 151 to the first hot turbine portion 161-1 of the dual flow turbine, and the supply pipe 126 supplies the steam from the second reheater 151. Supply to the second hot turbine portion 162-1 of the dual flow turbine. The outlet of the first hot turbine section 161-1 of the dual flow turbine 164 is connected to the supply pipe 128 of the cold section 161-2 of the first intermediate pressure turbine. The cold section 161-2 of the first intermediate pressure turbine is a double flow turbine, the outlet of which is connected to the second reheater 152 via a return pipe 125.

  The outlet of the second hot turbine section 162-1 of the dual flow turbine 164 is connected to the supply pipe 129 of the cold section 162-2 of the second intermediate pressure turbine. The cold section 162-2 of the second medium pressure turbine is a dual flow turbine with an outlet coupled to the supply pipe 127, which is used to expand the steam to a final condensed state. Deliver to one or more low pressure or LP turbines 163. The LP turbine 163 is configured as a so-called “double flow” turbine with two balanced branches in one inner casing. In an embodiment, a single dual-flow turbine 163 may be used such as one, two, three, four or five of such turbines, depending on the overall mass flow rate of steam through the plant. It represents any number of LP turbines.

  Since the present invention has been described as a complete example, the above modifications and others can be made within the scope of the invention. For example, in a smaller plant design, the second portions 161-2, 162-2 of the first and second medium pressure turbines may be replaced by 1 instead of forming two separate double flow turbines in the above embodiment. Can be combined into two dual flow turbines. For a dual flow turbine casing, multiple embodiments including a common outer casing and a common inner casing are possible, but with a design comprising one inner casing and a piston and blade carrier on the second side, both sides A common inner inlet casing with a blade carrier is also possible.

  The invention may be any individual feature described or implied herein or shown or implied in any drawing, or any combination of any such features, or any generalization of any such feature or combination. And those that are extended to their equivalents. In other words, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments. Unless expressly stated to the contrary, alternative features serving the same, equivalent, or similar purpose may be substituted for each feature disclosed in the specification, including the drawings.

  Unless expressly stated herein, any prior art description throughout the specification shall be recognized that such prior art is well known or forms part of common general knowledge in the art. is not.

DESCRIPTION OF SYMBOLS 10 Power plant 11 Steam generator 121 Main steam supply pipe 131 Main steam inlet valve 14 HP turbine 122 Outlet pipe 123 1st reheater return pipe 151 1st reheater 124 Supply pipe 132 Inlet valve 161 (1st ) IP turbine 161-1 (first) IP turbine hot part 161-2 (first) IP turbine cold part 128 supply pipe 125 return pipe 152 second reheater 126 steam supply pipe 133 valve 162 (second ) IP turbine 162-1 (second) IP turbine hot part 162-2 (second) IP turbine cold part 129 supply pipe 127 supply pipe 163 LP turbine 164 double flow turbine casing

Claims (7)

A steam power plant (10), at least one high pressure turbine (14) or turbine section having a steam outlet (122) connected in operation to a first steam reheater (151) in one rotor. And at least two intermediate pressure turbines (161, 162) or turbine section, the first of the at least two intermediate pressure turbines (161, 162) or turbine section being the second during operation. A steam outlet (125) connected to the steam reheater (152) of the at least two intermediate pressure turbines (161, 162) or a second of the turbine sections, the second steam A steam inlet (126) for receiving steam from the reheater (152) and one or more low pressure turbines (163) or turbines A steam outlet (127) connected to the section, wherein the at least two intermediate pressure turbines (161, 162) or turbine sections are respectively hot turbines (161-1, 162-1) or turbine sections; Separated into a cryogenic turbine (161-2, 162-2) or turbine section;
The first one of the at least two intermediate pressure turbines (161, 162), the high temperature turbine (161-1) or turbine section, and the second of the at least two intermediate pressure turbines (161, 162). However, the high temperature turbine (162-1) or turbine section is combined in a double flow configuration in one outer casing for the first of the at least two medium pressure turbines (161, 162). Separate steam inlet (128) and outlet pipe (125) and a second one of the at least two intermediate pressure turbines (161, 162) for the cold turbine (162-2) or turbine section Steam inlet (129) and outlet pipe (127). Plant (10).   A steam inlet (124) of the high temperature turbine (161-1, 162-1) or turbine section of the first of the at least two intermediate pressure turbines (161, 162) is connected to the first reheater ( 151) and the high temperature turbine (161-1) or steam outlet (128) of the turbine section of the first of the at least two intermediate pressure turbines (161, 162) Is connected to a separate cryogenic turbine (161-2) or turbine section of the first of the at least two intermediate pressure turbines (161, 162), and the at least two intermediate pressure turbines (161 , 162) of the first of the cryogenic turbine (161-2) or turbine section steam outlet (12 ) Is return pipe (125) is connected to the second reheater (152) via a steam power plant according to claim 1, wherein (10).   The high temperature turbine (162-1) or turbine section steam inlet (126) of a second of the at least two intermediate pressure turbines (161, 162) is an outlet of the second reheater (152). The high temperature turbine (162-1) or turbine section steam outlet (129) of the second of the at least two intermediate pressure turbines (161, 162) via a pipe connection, A second of the at least two intermediate pressure turbines (161, 162) connected to a separate cryogenic turbine (162-2) or turbine section of the at least two intermediate pressure turbines (161, 162); The steam outlet of the second of the cryogenic turbines (162-2) or turbine section is connected to the supply pipe (127 At least one is connected to a low pressure turbine (163), the steam power plant of claim 1, wherein through (10).   The high temperature turbine (161-1) or turbine section steam inlet (124) of the first of the at least two intermediate pressure turbines (161, 162) is an outlet of the first reheater (151). The high temperature turbine (161-1) or turbine section steam outlet (128) of the first of the at least two intermediate pressure turbines (161, 162) via a pipe connection, A first one of the at least two intermediate pressure turbines (161, 162) connected to a separate cryogenic turbine (161-2) or turbine section of the at least two intermediate pressure turbines (161, 162); The cold turbine (161-2) or turbine section steam outlet (125) of the first one is returned Connected to the second reheater (152) via (125), the second one of the at least two intermediate pressure turbines (161, 162) being the high temperature turbine (162-1) or A steam inlet (126) of the turbine section is connected to an outlet of the second reheater (152), and the high temperature turbine of the second of the at least two intermediate pressure turbines (161, 162). (162) or a steam outlet (129) of the turbine section is connected to a separate cryogenic turbine (162-2) of the second of the at least two intermediate pressure turbines (161, 162) via a pipe connection. Alternatively, the cryogenic turbine (1) connected to a turbine section and of a second one of the at least two intermediate pressure turbines (161, 162) 2-2) or vapor outlet of the turbine section (127) via a supply pipe (127) is connected to at least one low-pressure turbine (163), the steam power plant of claim 1 wherein (10).   The first of the at least two intermediate pressure turbines (161, 162), the cold turbine (161-2) or turbine section, and the second of the at least two intermediate pressure turbines (161, 162). The steam power generation of claim 1, wherein at least one of the cold turbine (162-2) or turbine section or the high temperature turbine (162-1) or turbine section of the object is a double flow turbine in one inner casing. Plant (10).   The first one of the at least two intermediate pressure turbines (161, 162), the high temperature turbine (161-1) or turbine section, and the second of the at least two intermediate pressure turbines (161, 162). The steam power plant (10) of claim 1, wherein the hot turbine (162-1) or turbine section is manufactured to withstand a respective steam inlet temperature of 650 ° C or higher.   The first one of the at least two intermediate pressure turbines (161, 162), the high temperature turbine (161-1) or turbine section, and the second of the at least two intermediate pressure turbines (161, 162). However, the high temperature turbine (162-1) or turbine section is manufactured to withstand a respective steam inlet temperature of 650 ° C. or more, and is the first of the at least two medium pressure turbines (161, 162). The cold turbine (161-2) or turbine section of the first and the cold turbine (162-2) or turbine section of the second of the at least two medium pressure turbines (161, 162) are 650 ° C. The steam power generator of claim 1, wherein the steam generator is manufactured for a steam inlet temperature of less than Door (10).

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