STEAM GENERATOR WITH ATTEMPERATORS

Abstract

An advantage steam generator and a steam generation system with an arrangement of heat-exchangers within a hot gas path. To protect the facilities and to increase the efficiency at least at the output of several heat-exchangers an attemperator is arranged, wherein each of them is connected via a fluid distribution valve with a distribution piping.

Claims

1-10. (canceled)

11. A steam generator with a hot gas path comprising: a superheater, which has a superheater output to deliver a flow of hot steam; at least four heat exchangers; an economizer; and a distribution piping, wherein the superheater and the heat exchangers and the economizer are connected in series and each comprises a fluid input and at least one fluid distribution pipe and several heat exchange tubes arranged inside the hot gas path and at least one collection pipe and a fluid output, wherein the economizer input is connected with a source of cold fluid, wherein: at the superheater output and in the connection between the superheater and a first heat exchanger and in each connection between one heat exchanger and the respective next heat exchanger of the at least four heat exchangers at least one attemperator is arranged, wherein the distribution piping is connected with the source of cold fluid and with the economizer output and via respective valves with each of the attemperators.

12. The steam generator according to claim 11, wherein: a main valve is arranged at the fluid input of a last heat exchanger in the series of heat exchangers; and/or a fluid supply valve is arranged at the economizer input; and/or a fluid bypass valve is arranged between the source of cold fluid and the distribution piping.

13. The steam generator according to claim 11, wherein at least at one of the series of superheater and heat exchangers comprises at least two collection pipes each with an attemperator, in particular each of them is connected via a respective fluid distribution valve with the distribution piping.

14. A steam generating system with a steam generator according to claim 11, further comprising: a control system, wherein the control system is able to control the fluid valves; and a temperature determination system, which is able to determine the temperature of at least one of the fluid outputs and/or the fluid inputs; and/or a vapor determination system, which is able to determine a share of vapor before and/or after at least one of the attemperators.

15. The steam generating system according to claim 14, wherein: the temperature determination system is able to determine the temperature of each of the fluid outputs and/or the fluid inputs; and/or the vapor determination system is able to determine the share of vapor at each of the attemperators.

16. The steam generating system according to claim 14, wherein the control system is able to control the fluid valves separately and in groups and stepwise; in particular dependent to the temperature of the fluid outputs and/or dependent to the share of vapor at the attemperators.

17. A method to control a steam generating system according to claim 14, comprising the steps: a) determine at least on temperature and/or temperature change at a fluid output; b) compare the temperature/temperature change with a predetermined value; and c) control at least one of the several fluid valves dependent on the comparison.

18. The method to control a steam generating system according to claim 17, comprising the steps: a) determine at least on share of vapor at an attemperator; b) compare the share of vapor with a predetermined value; and c) control at least one of the several fluid valves dependent on the comparison.

19. The method according to claim 17, wherein: the temperature and/or the temperature change at all fluid outputs is determined; and/or the share of vapor at all attemperators is determined.

20. The method according to claim 18, wherein the first and/or second and/or third and/or in particular fourth predetermined share of vapor is at least 60%, in particular at least 75%, and/or at most 90%, in particular at most 85%, of the mass flow.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0127] The following figures shows two different examples for an implementation of the inventive solution at a steam generator:

[0128] FIG. 1 shows schematically a power plant with a steam generator;

[0129] FIG. 2 shows schematically a steam generator with a first version of a superheater with cooling nozzles; and

[0130] FIG. 3 shows schematically a steam generator with a second version of a superheater with cooling nozzles.

DETAILED DESCRIPTION

[0131] The FIG. 1 shows schematically a power plant 07 with a gas turbine 09 and a steam turbine 08 and further as main part of the invention the steam generator 01. The steam generator 01 comprises hot gas path 02 pass through the steam generator 01 from in hot gas input side to a waste gas output side.

[0132] In operation the gas turbine 09 delivers—while enabling the generation of electrical energy with a generator—a flow of hot gas to the hot gas input side of the steam generator 01. After passing through the hot gas path 02 the previous hot gas will leave the steam generator 01 with a reduced temperature as waste gas at the waste gas output side.

[0133] The steam generator 01 comprises further several heat exchangers 11, which 11 are arranged at least partly within a hot gas path 02. Within the heat exchangers 11 an evaporation fluid, e.g. water/steam, flows from the respective fluid input 13 to the respective fluid output 17 in a direction generally opposite to the hot gas and gets heated while the hot gas gets cooled.

[0134] As common usual the first heat exchanger along the hot gas path starting from the upstream hot gas input side is a so-called superheater 11A—see also FIG. 2. The fluid output line 12 is in connection with the steam turbine 02 to enable the further generation of electrical energy.

[0135] At the start-up of the power plant 07 or with a sudden increase of the necessary power to be delivered by the power plan 07 the gas turbine 09 increases its output of hot gas very quickly. This leads to the high increase of the heat input into the steam inside the superheater 11. This leads to high thermal stress at the steam turbine 08 and also at the piping inside the steam generator 01, e.g. the fluid output 17, and also for the piping from the steam generator 01 to the steam turbine 08.

[0136] Next, at common steam generators the fluid flows from one heat exchanger to the next heat exchanger with an increase of the temperature. But the share of vapor has not been considered for the design of a steam generator.

[0137] An example for the inventive steam generator 01 is shown schematically in FIG. 2 with a number of heat exchangers 11 and attemperators 22.

[0138] First, the steam generator 01 comprises as main part a casing with a hot gas path 02. The hot gas path 02 extends from an input opening, where hot gas 03 is brought into the hot gas path 02. While crossing the steam generator 01 the gas cools down and leaves as waste gas 04 at an output side the hot gas path 02.

[0139] The steam generator comprises further several heat exchangers 11A-G. Those are arranged in this example adjacent to each other, whereby they could be also arranged with other elements in-between or in another order.

[0140] Here, the heat exchanger close to the hot gas input is a so-called superheater 11A. It 11A comprises a superheater fluid input 13A, wherein a superheater fluid output 17A of the superheater 11A delivers a stream of hot steam 05 and is connected with the steam turbine 08.

[0141] Next to the superheater 11A a first heat exchanger 11B is arranged. This 11B comprises analog a first fluid input 13B and a first fluid output 17B, whereby the first output 17B is connected with the superheater input 13A.

[0142] In the same way next to the first heat exchanger 11B a second heat exchanger 11C is arranged. This 11B comprises analog a second fluid input 13C and a second fluid output 17C, whereby the second output 17C is connected with the first input 13B.

[0143] Further next to the second heat exchanger 11C a third heat exchanger 11D is arranged. This 11D comprises analog a third input 13D and a third output 17D, whereby the third output 17D2 is connected with the second input 13C.

[0144] One more next to the third heat exchanger 11D a fourth heat exchanger 11E is arranged. This 11E comprises analog a fourth input 13E and a fourth output 17E, whereby the fourth output 17E is connected with the third input 13D.

[0145] And again, next to the fourth heat exchanger 11E a fifth heat exchanger 11F is arranged. This 11F comprises analog a fifth input 13F and a fifth output 17F, whereby the fifth output 17F is connected with the fourth input 13E.

[0146] As last in the row within the hot gas path 02 an economizer 11G is arranged. This 11G comprises analog an economizer fluid input 13G and an economizer fluid output 17G. Here the economizer output 17G is connected with the fifth input 13F.

[0147] Each of the superheater 11A and heat-exchangers 11B-11F enables and the economizer 11G enable the transfer of the heat from the hot gas 03 onto the fluid steam crossing the respective superheater 11A and heat-exchangers 11A-11F and economizer 11G. On the respective fluid input 13 a fluid steam with a less high temperature and with a lower share of vapor is supplied. After the heat transfer the fluid stream leaves the respective fluid output 17 with a higher temperature and with a higher share of vapor.

[0148] The economizer input 13G is connected with a source of cold fluid 24. This is regular cold water. To control the flow of cold fluid through the economizer 11G a fluid supply valve 25 is arranged within the connection from the source of cold fluid 24 to the economizer input 13G.

[0149] During operation the cold fluid from the source of cold fluid 24 should be heated in the economizer 11G by the usage of the remaining heat within the gas flowing through the hot gas path 02 up to a preferred temperature close the evaporation temperature but not exceeding this point. As result a hot, not evaporated fluid leaves the economizer 11G at the economizer output 17G.

[0150] To supply the following last heat-exchanger, namely the fifth heat exchanger 11F, with sufficient fluid flow in all situations at the fluid input 13F of the last heat exchanger a bypass line connects the source of cold fluid 24 with connection from the economizer output 17G to the last fluid input 13F. It is obvious, that further a fluid bypass valve 27 is necessary to control the flow of cold fluid through the bypass.

[0151] To enable a control of the flow of hot fluid from the economizer 11G and/or the flow of cold fluid from the bypass into the last heat-exchanger, namely the fifth heat exchanger 11F a main fluid valve 26 is arranged at the last fluid input 13F.

[0152] Now in the series of heat exchangers, namely the fifth, the fourth, the third, the second, the first heat exchanger 11F, 11E, 11D, 11C, 11B and further the superheater 11A in each connection from one heat exchanger 11 to the next heat exchanger 11B-F respectively superheater 11A from the fluid output 17 to next fluid input 13 an attemperator 22F, 22D, 22C, 22B is arranged. To enable the function of the attemperators 22 each of them 22 is connected with a distribution piping 21 to supply the respective attemperator 22 with a flow of not evaporated fluid.

[0153] In this solution the distribution piping 21 is then further connected with the economizer output 17G and through the bypass to the source of cold fluid 24 to guarantee a fluid “free of vapor” in the distribution piping 21. The arrangement of a main valve 26 at the input of the last heat exchanger 11F also affects the flow of fluid from the economizer 11A into the distribution piping 21. Further the flow of fluid from the source of cold 24 fluid through the bypass to the distribution piping 21 is controlled by a fluid bypass valve 27 within the bypass.

[0154] To enable a protection of following facilities from a too fast increase of the temperature of the hot steam 05 leaving the steam generator 01, a main attemperator 22A is arranged at the superheater output 17A. This attemperator 22A is also connected with the distribution piping 21, whereby a fluid distribution valve 23A is arranged to control the flow of fluid from the distribution piping 21 into the main attemperator 22A.

[0155] To enables the possibility to control the temperature of the fluid/steam flowing from one heat exchanger 11 to the next heat exchanger 11B-F respectively superheater 11A and furthermore to control the share of vapor at the input of each of the respective heat-exchangers 11B-F/superheater 11A it is necessary to arrange fluid distribution valves 23A, 23B, 23C, 23D, 23E, 23F within each connection from the respective attemperator 22B-F to the distribution piping 21.

[0156] An exemplary solution for an advantage implementation of the invention in further detail at a heat exchanger/superheater 11 is shown in FIG. 3. Here only the relevant part of the steam generator 01 is pictured with the section of the hot gas path 02 and the arrangement of one heat exchanger 11.

[0157] The heat exchanger 11B-11F or superheater 11A comprises a piping with the fluid input 13, which 13 is in connection with forgoing heat exchanger (not shown in this figure). From the fluid input 13 two (exemplary) distribution pipes 14.1 and 14.2 branches off. Several heat exchangers tubes 15 are each connected to one of the distribution pipes 14. On the other end of the heat exchange tubes 18 collection pipes 16.1 and 16.2 are arranged, which 16 then are in connection with the fluid output 17.

[0158] In operation a fluid steam 12 with a lower temperature is supplied to the fluid supply line 13. The steam flows through the distribution pipes 14 into the heat exchange tubes 15, where the heat is transferred from the hot gas inside the hot gas path 02 onto the fluid steam inside the heat exchange tubes 15. Then the hot fluid steam is collected in the collection pipes 16 and transferred to the fluid output 17 and leaves the heat exchanger/superheater 11 as fluid steam 18 with a higher temperature.

[0159] To enable a temperature control of the temperature and the share of vapor of the hot steam 18 attemperators 22.1, 22.2 are arranged. Therefore, in this advantage solution an attemperator 22.1 22.1 and 22.2 is arranged within each of the collection pipes 16.1 and 16.2. The attemperators 22 are supplied with a cooling fluid, e.g. water, from the distribution piping 21. To enable a control of the cooling fluid within each supply line to the attemperators 22.1, 22.2 fluid distribution valves 23.1 and 23.2 are arranged.

[0160] It should be noted, that in an extensive implementation of the forgoing solution it is possible to arrange an attemperator within the end of each heat transfer tube 15.

[0161] Regarding the description of the drawings it should be noted, that 11 represents any of the superheater 11A or heat-exchangers 11B-11F or economizer 11G (same with the fluid input 13, fluid output 17). Further 22 represents any attemperator 22A-22B or 22.1 or 22.2 (same with the fluid distribution valves 23)

LIST OF REFERENCE NUMBERS

[0162] 01 steam generator [0163] 02 hot gas path [0164] 03 hot gas [0165] 04 waste gas [0166] 05 hot steam output [0167] 07 power plant [0168] 08 steam turbine [0169] 09 gas turbine [0170] 11A superheater [0171] 11B-F first-fifth heat exchanger [0172] 11G economizer [0173] 12 fluid with lower temperature [0174] 13,13A-G input [0175] 14.1,14.2 distribution pipe [0176] 15 heat exchange tubes [0177] 16.1,16.2 collection pipe [0178] 17,17A-G output [0179] 18 fluid with higher temperature [0180] 21 distribution piping [0181] 22,22.1,22.2,22A-F attemperator [0182] 23,23.1,23.2,23A-F fluid distribution valve [0183] 24 cold water supply [0184] 25 water supply valve [0185] 26 main valve [0186] 27 water bypass valve