Operation of a gas turbine plant having a compressor and a turbine

Abstract

A method for operating a gas turbine plant having a compressor and a turbine, where a limit value of a guide blade adjustment for the compressor of the gas turbine is identified depending on at least one drive shaft speed of the gas turbine plant. For the at least one drive shaft speed, a maximum allowable turbine entry temperature corresponding to the limit value of the guide vane adjustment for the compressor or a maximum allowable temperature for the turbine of the gas turbine, which is dependent on the turbine entry temperature, is identified. The gas turbine is operated in consideration of the identified maximum allowable turbine entry temperature or the identified maximum allowable temperature.

Claims

1. A method for operating a gas turbine plant comprising a compressor and a turbine, the method comprising: identifying a limit value of a guide blade adjustment for the compressor of the gas turbine plant associated with a drive shaft speed using first data that correlate limit values with control variables, wherein each control variable of the control variables is based on a respective drive shaft speed, identifying a maximum allowable turbine entry temperature, or a maximum allowable temperature that correlates to a turbine entry temperature, for the identified limit value using second data that correlate the limit values with the maximum allowable turbine entry temperature or with the maximum allowable temperature, and operating the gas turbine plant at the drive shaft speed without exceeding the maximum allowable turbine entry temperature or the maximum allowable temperature.

2. The method as claimed in claim 1, wherein the limit value of the guide blade adjustment for the compressor of the gas turbine plant is selected to prevent an impairment of the operation of the gas turbine plant.

3. The method as claimed in claim 2, wherein the impairment comprises compressor pumping or compressor icing-up.

4. The method as claimed in claim 1, wherein the maximum allowable turbine entry temperature or the maximum allowable temperature is identified in further dependence on: a compressor inlet temperature and/or a compressor inlet moisture.

5. The method as claimed in claim 1, wherein the method is performed respectively for a plurality of predefinable points in time.

6. The method as claimed in claim 5, wherein the plurality of predefinable points in time lie within a turn-up operation of the gas turbine plant.

7. The method as claimed in claim 1, further comprising controlling and regulating the operation of the gas turbine plant.

8. An arrangement for controlling a gas turbine plant comprising a compressor and a turbine, comprising: an identification apparatus configured to perform the method as claimed in claim 1.

9. A gas turbine plant comprising: a compressor and a turbine, and an arrangement as claimed in claim 8.

10. The method as claimed in claim 1, wherein each control variable is further based on a compressor inlet temperature.

11. The method as claimed in claim 1, wherein the identified limit value applies to at least one row of guide blades downstream of a row of inlet guide vanes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the figures:

(2) FIG. 1 shows a sectional view through a gas turbine plant according to the invention with an arrangement for controlling the gas turbine plant,

(3) FIG. 2 shows a schematic view of a control of the operation of the gas turbine plant,

(4) FIG. 3 shows a diagram with a curve progression of the guide blade adjustment limit value in dependence on a variable nv,

(5) FIG. 4 shows a diagram with a curve progression of the maximum allowable turbine outlet temperature value in dependence on the variable nv,

(6) FIG. 5 shows a diagram with a curve progression of the maximum allowable turbine outlet temperature value in dependence on the compressor inlet temperature,

(7) FIG. 6 shows a further diagram with a curve progression of the maximum allowable turbine outlet temperature value in dependence on the guide blade adjustment limit value,

(8) FIG. 7 shows a diagram with a curve progression of the output of the gas turbine plant in dependence on the maximum allowable turbine outlet temperature value, and

(9) FIG. 8 shows a diagram with two curve progressions of a turbine entry temperature and a curve progression of the guide blade adjustment value, respectively over the compressor inlet temperature.

DETAILED DESCRIPTION OF INVENTION

(10) FIG. 1 shows a schematic view of a gas turbine plant 2. In the following text the terms gas turbine plant and gas turbine are used as equivalents. The gas turbine 2, in the main flow direction 4 of a flow medium 6 such as air, or in the longitudinal direction of a rotational axis 8, comprises, inter alia, a compressor inlet 10, a compressor 12, a guide blade adjustment means 14, a compressor outlet 16, a burner unit 18 and a turbine or turbine unit 20.

(11) The guide blade adjustment means 14, in the given exemplary embodiment, is shown in two pieces/is realized as being rotation-symmetric to the rotational axis 8, which of course does not, of necessity, have to be the case.

(12) In addition the gas turbine comprises a drive shaft 22, which is rotatable about the rotational axis 8 and extends along the gas turbine 2 in the longitudinal direction. The drive shaft 22 connects the turbine unit 20 with the compressor 12 in a fixed-drive/non-rotatable manner.

(13) The compressor 12 comprises a sequence of axially arranged compressor guide blade stages 24 and compressor blade stages 26. At least one stage or one row of compressor guide blades is prepared for adjusting, i.e. twisting against the main flow direction 4 of the flow medium 6, by means of the guide blade adjustment means 14.

(14) During an operation of the gas turbine 2 the flow medium 6 enters the compressor 12 through the compressor inlet 10. The flow medium 6 is compressed in the compressor 12 and thereby heated to between 300 C. and 500 C. The compressed flow medium 6 is admitted via the compressor outlet 16 to the burner unit 18, which for example may be realized in the form of a ring burner unit. The burner unit 18 comprises one or more combustion chambers 28, each with a burner 30.

(15) The compressed flow medium 6 coming from the compressor 12 is directed, at least proportionally, into the burner unit 18 or the combustion chamber 28 and mixed in there with a gaseous or liquid fuel. The ignitable mixture formed thus in the burner unit 18 is then ignited/burned, and the fuel gas or the working gas of the combustion is directed via a transition channel 32 to the turbine unit 20 of the gas turbine 2.

(16) The turbine unit 20 comprises a number of turbine wheels 34 connected to the drive shaft 22 with turbine blades 36. In addition turbine guide blades 38 are axially arranged between the turbine wheels 34. The turbine guide blades 38 of the turbine unit 20 are in turn connected to a stator 40.

(17) The combustion gas from the one or more combustion chambers 28 enters through the transition channel 32 into the turbine unit 20 and drives the turbine blades 36 in such a way as to rotationally drive the drive shaft 22 thus generating a torque about the rotational axis 8 of the gas turbine 2. The turbine guide blades 38 serve to direct the combustion gas/the working gas onto the turbine blades 36, i.e. they serve to guide the flow.

(18) The compressor blade stages 26 are driven by the drive shaft 22, i.e. by the torque generated in the turbine unit 20 and set into rotation about the rotational axis 8, wherein the compressed flow medium 6 is generated by the gas turbine 2 itself, as soon as this is in a corresponding operating state.

(19) The gas turbine 2 further comprises a control arrangement 42, which for better illustration is shown in FIG. 1 outside/constructionally separated from the gas turbine 2. The control arrangement 42 comprises an identification apparatus 44. The control arrangement 42 serves, inter alia, to control an operation of the gas turbine 2.

(20) The identification apparatus 44 is prepared for identification of at least one operating condition (drive shaft speed) of the gas turbine plant 2. In the exemplary embodiment given the identification apparatus 44 of the control arrangement 42 is prepared for an identification of the compressor inlet temperature and/or the compressor inlet moisture and/or a speed of the drive shaft 22. The identification apparatus is in addition configured such that the limit value 46 of the guide blade adjustment and the maximum allowable turbine outlet temperature value 48 can be identified.

(21) The control arrangement 42 can be prepared to activate the guide blade adjustment means 14 in order to initiate an adjustment of the compressor guide blade stages 24 against the main flow direction 4.

(22) A schematic view of a control of the operation of the gas turbine plant 2 is shown in FIG. 2 and will now be described. During an operation of the gas turbine plant 2 the flow medium 6 flows from an environment not described in detail into the compressor inlet 10 of the compressor 12 of the gas turbine plant 2. The flow medium 6 is compressed in the compressor 12, leaves the compressor 12 via the compressor outlet 16 and then reaches the burner unit 18.

(23) In the burner unit 18 an ignitable mixture is produced from the compressed flow medium 6 by admitting a fuel mass current 50, for example a mass current of a gas, and ignited, wherein ignition is in particular continuous.

(24) The ignited flow medium 6 leaves the burner unit 18 in main flow direction 4 (see FIG. 1) and enters the turbine unit 20 of the gas turbine plant 2 via the turbine entry 52 and sets the turbine wheels 34 (see FIG. 1) into rotation, such that a torque is transferred to the drive shaft 22.

(25) An output of the gas turbine plant 2 resulting from the torque generated in this way and the speed of the drive shaft 22 is transferred in part to the compressor 12 mounted on the drive shaft side for performing compression work. Another part of the output of the gas turbine plant 2 is transferred to a generator 54 as effective output and is converted therein into electric energy.

(26) Starting from a base load operation of the gas turbine plant 2 a so-called turn-up operation is then performed for operating the gas turbine plant 2 with an output above the base load, for example with 105% of the base load, in other words, the suction air mass current 56 is increased through an adjustment of the compressor inlet guide blades/one or more compressor guide blade stages 24 (see FIG. 1). Adjustment of the compressor guide blade stages 24 is effected by activating the guide blade adjustment means 14.

(27) The identification apparatus 44 of the control arrangement 42 detects or identifies a temperature value (the temperature) and a moisture value/a moistness value (the moisture, moistness) of the flow medium 6 entering at the compressor inlet 10, i.e. a compressor inlet temperature 58 and a compressor inlet moisture 60. Identification of the compressor inlet moisture 60 and the compressor inlet temperature 58 may e.g. be effected via correspondingly suitable sensors or via other measuring means, wherein the sensors or the measuring means may also be an integral component of the control arrangement 42. In addition the identification apparatus 44 detects or identifies the speed of the drive shaft 22, i.e. a drive shaft speed 62. In the case of a multi-shaft realization of the gas turbine plant 2 a speed of a shaft other than the drive shaft 22 may be identified instead of or in addition to, the drive shaft speed 62.

(28) In the exemplary embodiment given the identification apparatus 44 identifies the guide blade adjustment limit value 46 in dependence on the compressor inlet temperature 58 and the drive shaft speed 62. The guide blade adjustment limit value 46 is a limit value of the adjustment of the compressor guide blades 24 of the compressor 12, at which, when it is reached, exceeded, or not reached, the so-called compressor pumping is to be expected. Normally compressor pumping occurs more frequently at a raised compressor inlet temperature 58, in particular within a range of 20 C. to 50 C.

(29) In addition the identification apparatus 44 identifies the maximum allowable turbine outlet temperature value 48 in dependence on the compressor inlet temperature 58 and the drive shaft speed 62. Alternatively the maximum allowable turbine outlet temperature value 48 may also be identified in dependence on the guide blade adjustment limit value 46.

(30) By identifying the maximum allowable turbine outlet temperature value 48, adherence to a maximum allowable turbine entry temperature 64, which depends on a turbine outlet temperature 66, can be achieved in a turn-up operation of the gas turbine plant 2 by using downstream processing in the control arrangement/in a process control system of the gas turbine plant 2.

(31) FIG. 3 shows a diagram with a curve progression 68 of the guide blade adjustment limit value 46 (ordinate [%]) identified by the identification apparatus 44 (see FIG. 1, 2) in dependence on a variable nv 70 (abscissa [ ]). The variable nv is a variable which can be identified in dependence on the compressor inlet temperature 58 and the drive shaft speed 62 (see FIG. 2). Alternatively identification of the guide blade adjustment limit value 46 may be effected directly in dependence on the compressor inlet temperature 58 and the drive shaft speed 62.

(32) According to the curve progression 68 an nv value 72 identified in the given exemplary embodiment for a compressor inlet temperature 58 of 20 C. and a drive shaft speed 62 of 60 Hz, results in a guide blade adjustment limit value 74. A reduced nv value 76 results in a guide blade adjustment limit value 78, wherein the nv value 76 corresponds to a compressor inlet temperature 58 of 27 C. and a drive shaft speed 62 of again 60 Hz. A further reduced nv value 80 results in a guide blade adjustment limit value 82, wherein the nv value 80 corresponds to a compressor inlet temperature 58 of 50 C. and a drive shaft speed 62 of again 60 Hz. Therefore, for an unchanged drive shaft speed 62 and a compressor inlet temperature 58 rising from 20 C. (72), over 27 C. (76) to 50 C. (80), the guide blade adjustment limit value 46, dropsi.e. for a decreasing nv 70.

(33) Expressed in simplified terms, for an increasing compressor inlet temperature 58, in particular above 20 C. (i.e. below the nv value 72), only smaller guide blade adjustments are allowable in order to prevent compressor pumping. Below a compressor inlet temperature 58 of 20 C. (i.e. above the nv value 72) a constant guide blade adjustment limit value 74 prevails according to the curve progression 68.

(34) FIG. 4 shows a diagram with a curve progression 84 of the maximum allowable turbine outlet temperature value 48 (ordinate [ C.]) identified by the identification apparatus 44 (see FIG. 1, 2) in dependence on the variable nv 70 (abscissa [ ]). The nv values 72, 76 and 80 are identical with the values shown in FIG. 3.

(35) Starting from an nv value 80 and a maximum allowable turbine outlet temperature value 86, falling maximum allowable turbine outlet temperature values (88, 90) occur for a rising nv (76, 72). The curve progression 84 between the nv values 80 and 72 is non-linear. Above the nv value 72, i.e. below a compressor inlet temperature 58 of 20 C. for an unchanged drive shaft speed 64 of 60 Hz, the maximum allowable turbine outlet temperature value 90 remains constant within a certain range, wherein the drive shaft speed 64 may be a speed different from 60 Hz, in particular 50 Hz. Therefore higher turbine outlet temperatures 66 are allowable as the compressor inlet temperature 58 rises.

(36) FIG. 5 shows a diagram with a curve progression 85 of the maximum allowable turbine outlet temperature value 48 (ordinate [ C.]) in dependence on the compressor inlet temperature 58 (abscissa [ C.]). The maximum allowable turbine outlet temperature values 86, 88 and 90 are identical to the values indicated in FIG. 4.

(37) Starting from a compressor inlet temperature value 152 of 50 C. and a maximum allowable turbine outlet temperature value 86, as the compressor inlet temperature (154, 156) drops, the maximum allowable turbine outlet temperature values (88 (27 C.), 90 (20 C.)) drop. The curve progression 85 between the compressor inlet temperature values 152 (50 C.) and 156 (20 C.) is non-linear. Below the compressor inlet temperature value 156 of 20 C. for an unchanged drive shaft speed 64 of 60 Hz, the maximum allowable turbine outlet temperature value 90 remains constant within a certain range, wherein the drive shaft speed 64 may be different from 60 Hz, in particular it may be 50 Hz.

(38) FIG. 6 shows a further diagram with a curve progression 92 of the maximum allowable turbine outlet temperature value 48 (ordinate [ C.]), which may be identified by the identification apparatus 44 (see FIG. 1, 2). In this exemplary embodiment, identification, in contrast to the exemplary embodiment shown in FIG. 4, is effected in dependence on the guide blade adjustment limit value 46 (abscissa [%]). The guide blade adjustment limit values 82, 78 and 74 are identical to the values shown in FIG. 3.

(39) Starting from a guide blade adjustment limit value 82 and a maximum allowable turbine outlet temperature value 94 falling maximum allowable turbine outlet temperature values (96, 98) are experienced for a rising guide blade adjustment limit value (78, 74). The curve progression 92 between the guide blade adjustment limit values 82 and 100 is linear.

(40) Above the guide blade adjustment limit value 100 the maximum allowable turbine outlet temperature value 102 remains constant.

(41) Expressed in simplified terms, a rising turn-up or rising guide blade adjustment limit value 46 results in lower maximum allowable turbine outlet temperature values 48.

(42) FIG. 7 shows a diagram with a curve progression 104 of the output 106 of the gas turbine plant (ordinate [MW]) in dependence on the maximum allowable turbine outlet temperature value 48 (abscissa [ C.]). The curve progression 104 of the output 106 is achieved by adhering to a maximum allowable turbine entry temperature value 108 represented by the isotherm 110 as a dotted line. The noted down turbine outlet temperature values 94, 96 and 98 are identical to the values given in FIG. 5.

(43) The diagram shown in FIG. 6 makes it clear, how by influencing the maximum allowable turbine outlet temperature value 48 an increase in output of the gas turbine plant 2 (see FIG. 1, 2) can be achieved while adhering to the maximum allowable turbine entry temperature value 108/keeping it constant.

(44) Starting from a turbine outlet temperature value 94 and an output of the gas turbine plant 2 with an output value 112, an increase in output is achieved by increasing the mass current by opening the guide blade, whilst as a result of decreasing the TOTC an over-firing of the turbine is prevented/adherence to the allowable turbine entry temperature is ensured. Both the state 116 and the state 118 lie on the isotherm 110, i.e. the maximum allowable turbine entry temperature value 108 is adhered to, while increasing the output from the value 112 to the value 114.

(45) Furthermore starting from the turbine outlet temperature value 96 and the output value 114, by decreasing the turbine outlet temperature once again down to the turbine outlet temperature value 98, a further rise in output up to an output value 120 is achieved by opening the guide blade while adhering to the turbine entry temperature. The state 122 lies again on the isotherms 110, i.e. the maximum allowable turbine entry temperature value 108 is adhered to even during the rise in output from the value 114 to the value 120.

(46) In consequence the rise in output from the value 112 to the value 120 is achieved while by-passing an additional thermal stress on the turbine unit 20 of the gas turbine plant (see FIG. 1). This means that advantageously, operation of the gas turbine plant is possible, in particular also permanently in a so-called turn-up mode of operation, with reference to thermal stress on the turbine unit 20.

(47) FIG. 8 shows a diagram with two curve progressions 124, 126 of a turbine entry temperature 128 (left-hand ordinate [ C.]) in dependence on the compressor inlet temperature 58 (abscissa [ C.]). In addition a further curve progression 130 of a maximum allowable guide blade adjustment value 132 (right-hand ordinate [%]), is plotted, again over the compressor inlet temperature 58 (abscissa [ C.]).

(48) In the present exemplary embodiment a turn-up of the guide blade adjustment from a guide blade adjustment value 138 to a guide blade adjustment value 140 is effected over a rising compressor inlet temperature 58 from a compressor inlet temperature value 134 to a compressor inlet temperature value 136. For a further rise of the compressor inlet temperature 58 to a compressor inlet temperature value 142 no further turn-up is effected, i.e. the value of the guide blade adjustment is kept constant. Above the compressor inlet temperature value 142 an asymptotic reduction of the turn-up to a guide blade adjustment value 146 takes place up to a compressor inlet temperature value 144. Expressed in simple terms the guide blade adjustment is reduced in order to prevent or avoid compressor pumping.

(49) The curve progression 126 of the turbine entry temperature 128 corresponds to the described curve progression 130 of the guide blade adjustment value 132: over the rising compressor inlet temperature 58, i.e. starting from the compressor inlet temperature value 134 up to the compressor inlet temperature value 136, the turbine entry temperature value 128 rises from a turbine entry temperature value 148 to a maximum allowable turbine entry temperature value 150.

(50) With a further rise of the compressor inlet temperature 58 to the compressor inlet temperature value 142 no further increase in turbine entry temperature 128 takes place. I.e. the gas turbine is operated via a control of the maximum allowable turbine outlet temperature value 48 in dependence on the guide blade adjustment, the compressor inlet temperature 58 or the nv value (see FIG. 4, 5, 6, 7) such that over-firing of the turbine unit 20 (see FIG. 1) is avoided.

(51) Above the compressor inlet temperature value 142 up to a compressor inlet temperature value 144 an asymptotic reduction of the turbine entry temperature 128 to a turbine entry temperature value 152 takes place. The reduction in turbine entry temperature 128 results from the reduction, via control and regulation means, of the maximum allowable turbine outlet temperature value 48 in dependence on the guide blade adjustment value 132.

(52) The curve progression 124 shows a further control and regulation-based development, where even above the compressor inlet temperature value 142 the turbine entry temperature 128 can be kept constant, which is of advantage for the process. Keeping this temperature constant can be achieved by an alternative or extended identification of the maximum allowable turbine outlet temperature value 48.