With Fig. 1 one embodiment of the present of invention are described.
Exhausting recombustion equipment shown in Fig. 1, comprise suck air and compression compressor 1a, pressurized air and fuel mix also burning with the burner 1b of generation combustion gas and the gas turbine 1c that drives by the combustion gas that generated among the burner 1b.Then, along with the driving of gas turbine 1c, the generator that is connected with gas turbine 1c 5 drives and obtains electric power output.
On the other hand, the exhaust gas of discharging from gas turbine 1c is supplied with boiler 2 as combustion air, with fuel mix and burn it.In boiler 2, produce steam, produce steam driving steam turbine 3 with this.Then, along with the driving of steam turbine 3, the generator that is connected with steam turbine 36 drives and obtains electric power output.
Steam from steam turbine 3 is discharged condenses into condensed water (feedwater) in condenser 12, supply with boiler 2 once more.Exhaust gas from boiler 2 is discharged carries out discharging in atmosphere after the heat exchange with condensed water in gas feed water preheater 4.Moreover, at this moment preferably implement processing such as denitration, desulfurization.
In addition, in exhausting recombustion equipment, the boiler fueling of being supplied with to gas turbine and combustion turbine exhaustion gas respectively, fuel feed can be controlled respectively.Therefore, can control the output of gas turbine and the output of boiler respectively.
The steam turbine of this equipment of expression and the output balance of gas turbine among Fig. 2.In Fig. 2, transverse axis is represented gas turbine output, and the longitudinal axis is represented steam turbine output.The line of single-point among Fig. 2 is the common travel line of the behavior of gas turbine and steam turbine in the common operation occasion of expression.Thereby, move on this line at normal occasion steam turbine and gas turbine.In other words, in the little stage of the output of gas turbine, it is about 50% that steam turbine output is risen to, and then, steam turbine output kept substantially make gas turbine output rise to about 80% under the constant state.Then, while this output is risen.Become for 100% stage in gas turbine output, make steam turbine output rise to 100%.
The oblique line of Fig. 2 middle and upper part is partly represented uneven district, top.This is the situation that gas turbine output is little, steam turbine output is big.Steam turbine is output as near 100%, and gas turbine then is present in the very wide scope that outputs to high output from low.In addition, gas turbine is to become in about scope 80% or more in steam turbine output near 0% the time to take place, and along with the raising of gas turbine output, the steam turbine of the lower limit that this scope takes place is exported and also risen at leisure up to reaching 100%.
As an example in this imbalance district, along with the reduction of gas turbine output, the exhaust gas amount of gas turbine reduces, exist concerning boiler 2 become the combustion air amount low=scope of burns oxygen quantity not sufficient.If the burns oxygen quantity not sufficient takes place, then, control the fuel of supplying with boiler 2 so must reduce steam turbine output owing to causing boiler flame-out.
The reticulate pattern of lower right part is partly represented uneven district, bottom among Fig. 2.This is that gas turbine output is big, the situation that steam turbine output is little.
Betide near the gas turbine output 100% and steam turbine is output as the following occasion of 50%-60%.Steam turbine also descends in the output of the upper limit of this scope if the output of gas turbine reduces, and in the output about 80% of gas turbine, the output of steam turbine is reduced near 0%.
As an example in this imbalance district, along with the reduction of steam turbine output, the feedwater flow that passes through of gas feed water preheater 4 reduces, and exists the scope of vaporize in the inside of gas feed water preheater 4 or the economizer in the boiler 2 etc. (water is by vaporized).
The sharply occasion of decline of certain discomfort, gas turbine output takes place in gas turbine, if steam turbine output still keeps motionless, then might swarm into uneven district, top.
In combination plant, the output of steam turbine is general corresponding with the output of gas turbine.But in exhausting recombustion equipment, as mentioned above, because gas turbine not only, and in boiler, also can adjust fuel feed, so not corresponding operation is possible.Therefore, to move be important to the imbalance of considering both.
As the discomfort of gas turbine, can consider flame-out etc. the abnormal combustion of rising, the burner of decline, the exhaust gas temperature of fuel pressure, variance ratio and amplitude of variation that gas turbine output descends relate to many aspects.
Because the discomfort of gas turbine, make gas turbine output be reduced to the occasion of predetermined value, corresponding with the reason of the discomfort of gas turbine, will be reduced to necessary output respectively.
For example, in the occasion of the gas turbine of the two-stage combustion device that has the second level burning portion that comprises the first-stage burning portion that carries out diffusive combustion and carry out pre-mixing combustion, the only first-stage burning portion operation that often carries out the transition to when unusual such as flame-out takes place in secondary firing portion.In this occasion, gas turbine output often is reduced to 50% from 100%.The occasion of being made up of controllable a plurality of fuel system in pre-mixing combustion portion, it is just passable often to reduce the unusual fuel system share of generation.In pre-mixing combustion portion, have in the occasion of four fuel system, just reduce the share that fuel system is born during a system generation abnormal combustion from 100%.Moreover the gas turbine output that waits the discomfort of gas turbine to cause unusually by burner descends, and often controls sharp with the output variance ratio of per second a few percent to percent tens.
Therefore, degradation under the common output in the output of gas turbine can be according to the common travel line of being put down in writing among Fig. 2 described later for example, controls the output of steam turbine accordingly with the output of gas turbine.Detecting expression, preferably carry out and the different control of hereinafter describing in detail of travel line usually as mentioned above based on the occasion of the anomalous signals of the discomfort of gas turbine etc.
The reason that output sharply descends as gas turbine in exhausting recombustion equipment can be considered all situations like this.In order no matter in any discomfort of gas turbine, to reduce steam turbine output safely, as the steam power generating equipment of prior art, always steam turbine output is being reduced in the method for predetermined constant output, might swarming into the uneven district of output of steam turbine and gas turbine.
Thereby, avoid uneven district, described top and uneven district, described bottom, set the operational limit scope between the dotted portion in the image pattern 2 like that, substantially be to take such operation method, promptly in this scope, move all only allowing under any running state, when gas turbine output descends, should within described operational limit scope, reduce steam turbine and export.
In order in this scope, to move, in this embodiment, as shown in fig. 1 signal input control device 11 from generator 5 and generator 6.In control gear 11,, reduce steam turbine output according to this input signal with predetermined operational limit scope.Specifically, turn down the valve 10 of controlling the fuel quantity of supplying with boiler 2, reduce fuel quantity.Perhaps, though do not illustrate among Fig. 1, also can reduce the vapor volume of supplying with steam turbine.
In addition, control gear 11 can be set steam turbine output and reduce line, when the output of gas turbine descends, reduces steam turbine output according to predetermined operating mode.
Described output reduce line be set at lower than uneven district, top, than in the high operational limit scope in uneven district, bottom, can be used for setting the steam turbine target corresponding and export with gas turbine output.
For example, it is such that steam turbine shown in the double dot dash line 100 in the image pattern 2 is exported the automatic line of return 100,101, in predetermined operational limit scope, can form the steam turbine output that the point from the point of gas turbine output 100%, steam turbine output 100% to gas turbine output 20%, steam turbine output 50% reduces point-blank and reduce line.Whereby, can simplify control circuit in the control gear 11.
As the automatic line of return 100,101, the automatic line of return of the occasion that descends except the output of gas turbine and the steam turbine state output from 100%, that preferably sets output with gas turbine respectively and be not 100% occasion respectively exports the corresponding automatic line of return.When causing that by the discomfort of gas turbine output descends under gas turbine part output state, it is possible that the steam turbine output that the state of the gas turbine output before descending with output adapts descends.
Set steam turbine and export the automatic line of return, reduce steam turbine output, desirable steam turbine output is more only set for, can set the steam turbine output order as the function of gas turbine output at gas turbine output arbitrarily along this line.
In addition, steam turbine shown in the double dot dash line among Fig. 2 101 is exported the automatic line of return, place in the predetermined operational limit scope, by setting the upper limit of described operational limit scope, the steam turbine output slippage in the time of can descending gas turbine output reduces to minimum.The upper limit of so-called described operational limit scope is for the maximum point of same gas turbine output steam turbine output, along the occasion of this line reduction steam turbine output, can guarantee maximum output for outfit of equipment.
Adopt the occasion of the described automatic line of return 100,101, at steam turbine is not under the part output state of 100% output, because causing gas turbine, gas turbine discomfort etc. exporting the occasion that descends, the target output of the steam turbine corresponding with the gas turbine output that descends, than the decline of corresponding gas turbine output and the also high occasion of steam turbine output before reducing, even also may be controlled to gas turbine output decline takes place, steam turbine output is also still remained stationary.
Whereby, corresponding gas turbine output descends, and suppresses state that steam turbine output is risen separately, can easily carry out the control of gas turbine and steam turbine.
In addition, preferably common travel line is set for the automatic line of return and had such scope, compare with steam turbine output, want high according to the steam turbine output of the described automatic line of return of same gas turbine outlet according to the described common travel line of predetermined gas turbine outlet.
With because the gas turbine output of gas turbine discomfort etc. descends corresponding, reduce when the steam turbine output, in described operational limit scope, because the steam turbine that steam turbine output is higher than on the common travel line is exported, suppress fewly so can descend output as outfit of equipment.
In addition, the output reduction method of exhausting recombustion equipment of the present invention is when the output of described gas turbine sharply descends, in the predetermined operational limit scope of described gas turbine and the operation of described steamer function, operating mode according to predetermined reduces the output of described steam turbine.
An embodiment of expression control circuit among Fig. 3.The control circuit of controlling the output of steam turbine etc. according to common travel line of Fig. 2 omits.Automatically return if gas turbine takes place, then the output of gas turbine powered generator 5 descends.According to this output, export the automatic line of return according to predetermined steam turbine and set steam turbine and return target output automatically.Send the instruction that reduces steam turbine output, reduce steam turbine output, up to reaching this output.Moreover; steam turbine is exported the automatic line of return and ought to be set in beyond the uneven district of output of steam turbine and gas turbine; but as protection owing to the excessive occasion that descends of certain unusual steam turbine output; for the purpose of prudent, with the condition of the uneven district of the output that does not enter steam turbine and gas turbine as the output reduction.
Specifically, for example operation as following.
The occasion that descends owing to described such discomfort in the actual output of gas turbine, with the actual output input of the gas turbine steam turbine-uneven district of gas turbine output determining device, for example, in the occasion that does not enter the imbalance district shown in Fig. 2, signal be sent to " with " part.
On the other hand, the actual output input of gas turbine steam turbine is returned target output setting device automatically, export the automatic line of return according to for example steam turbine shown in Fig. 2, calculate and the corresponding steam turbine output of the actual output of gas turbine, the signal of being calculated (A) input comparator.Input described signal of calculating (A) and the steam turbine real output signal (B) imported in comparator, in the occasion of A<B, described signal of calculating (A) be sent to " with " part.
" with " part, having imported the occasion that the signal that returns automatically of gas turbine has taken place in described signal, described signal of calculating (A) and expression of sending in the occasion that does not enter uneven district, the target output of described signal of calculating (A) steam turbine that output reduces as steam turbine is exported.
Automatically the signal that returns has taken place in described expression, for example, and can be with the signal of the discomfort of representing described gas turbine.
As the output of the gas turbine and the steam turbine of the setting that is used for described operational limit scope, can select for use output order or reality to export both respectively.
If the use output order then need not receive actual output from the outside of control circuit, the formation of circuit can be simplified, and in addition, if use actual output, then can positively set described operational limit scope.Thereby, will use respectively according to the characteristic that constitutes machine.
In the present embodiment, no matter in the occasion of any discomfort, also little amplitude ground reduces steam turbine output, is effective.Particularly, in exhausting recombustion equipment, though in the scope that steam turbine output is little in that the peculiar gas turbine output of exhausting recombustion equipment is big the operation restricted area is arranged also, in the present embodiment, do not swarm into the possibility in this district, can not cause significantly output loss in addition yet.
According to present embodiment, set the operational limit scope of exporting with the corresponding steam turbine of decline of gas turbine output, only in this scope, move by restriction, even when gas turbine output sharply descends, also can avoid swarming into the imbalance district.In this occasion, the operational limit scope will be avoided uneven district certainly and set.
With the free-throw line in the operational limit scope is that steam turbine is exported the automatic line of return, by only reduce steam turbine output on this line, can simplify the formation of concrete control circuit.In other words, this is because by at the output of gas turbine arbitrarily desirable steam turbine output more only being set for, the cause that can set the function that the steam turbine output order is exported as gas turbine.In addition, by steam turbine being exported the upper limit that the automatic line of return is set the operational limit field for, the steam turbine output slippage in the time of can descending gas turbine output reduces to minimum.The upper limit of so-called operational limit scope is for the maximum point of same gas turbine output steam turbine output, by reduce steam turbine output along this line, can guarantee maximum steam turbine output.As the output of the gas turbine and the steam turbine of the setting that is used for the operational limit scope, can select for use output order or reality to export both respectively.If use output order then the formation of control circuit can be simplified, if use actual output then can positively set the operational limit scope.
In addition, another embodiment of expression control circuit among Fig. 4.
After the output of input gas turbine, in steam turbine upper limit setting device, export corresponding steam turbine output CLV ceiling limit value with regard to the gas turbine of calculating Yu imported.In addition, meanwhile, in steam turbine plus-minus output setting device, calculate with the gas turbine of being imported and export corresponding steam turbine output plus-minus setting value.
Here, in described output upper limit setting device, described steam turbine is exported upper limit set value, is considered to uneven district, described top to have nothing to do, and uses at the function of gas turbine output and represents.Thereby can set the steam turbine target output of exporting the corresponding upper limit with gas turbine.
In addition, in described bottoming setting device, be considered to uneven district, described bottom irrelevantly too, described setting value is used at the function of gas turbine output and is represented.Thereby can set with gas turbine and export corresponding lower limit steam turbine target output.
Upper limit setting signal from described output upper limit setting device is input to rate of change limit device (RL).The rate of change limit of load can be set for example one of per minute percentage or a few percent etc. for.Here, behind the signal that returns automatically of input expression gas turbine, rate of change limit just is disengaged.So, be input to the preferential device of low value.
Automatically the signal that returns takes place in described expression, can be with the signal of the described discomfort of representing gas turbine some.
On the other hand, from the lower limit set signal of described bottoming setting device, be input to the preferential device of high value.Moreover, as shown in the figure,, also can be input to the preferential device of high value through rate of change limit device (RL) from the lower limit set signal of lower limit set device.In this rate of change limit device, apply for example foregoing predetermined rate of change limit.Steam turbine output setting signal is input to the preferential device of high value.This for example is the output setting signal of the steam turbine of reality.Then, by the preferential device of high value the signal of high value in the signal of being imported is input to the preferential device of described low value.
Require signal output by the preferential device of low value exporting as steam turbine from the signal of rate of change limit device and from the low value in the signal of the preferential device of high value.
Whereby, even, can suppress the imbalance of gas turbine and steam turbine because the occasion of the discomfort of generation gas turbine etc. when gas turbine output sharply descends, also can reduce steam turbine output in the operational limit scope.In addition, even in the rapid occasion that descends of gas turbine output, also can in the operational limit scope, maintain high output to steam turbine output.
Specifically, for example in having the gas turbine of two stage burner, automatically return to the operation of only first-stage burning portion owing to the part of the second level burning portion of burner is flame-out, gas turbine output drops sharply to 50% occasion from 100%, just can be in the common relevant rate of change limit of setting with the steam turbine output upper limit of signal of removing as previously mentioned in service, make steam turbine output not swarm into uneven district on one side, Yi Bian keep high steam turbine output.
In addition, the output setting signal of the described steam turbine of the preferential device of the described high value of input also can be the signal of exporting from common steam turbine output setting device.
Usually steam turbine output setting device according to the common travel line shown in described Fig. 2, is exported and the corresponding steam turbine output of the gas turbine output signal of being imported.
When moving usually, in general, become the steam turbine output of described high preferential device of value and the preferential device of described low value, selecting from the signal of exporting about common steam turbine output setting device and require signal.
In the occasion of gas turbine discomfort, in preferential device of high value or the preferential device of low value, not described steam turbine output setting signal but other signal is selected, become steam turbine output and require signal.
Moreover, for further simplified system, also can make in being constrained to the restriction that does not enter uneven district, described top or uneven district, bottom, only adopt the actual motion control gear of a necessary side's restriction especially.
Whereby, no matter in the occasion of any discomfort, also little amplitude ground reduces steam turbine output, is effective.Particularly, in exhausting recombustion equipment, though in the scope that steam turbine output is little in that the peculiar gas turbine output of exhausting recombustion equipment is big the operation restricted area is arranged also, in the present embodiment, do not swarm into the possibility in this district, can not cause significantly output loss in addition yet.
Particularly, present embodiment is relevant with exhausting recombustion equipment, the so-called exhaust reheating equipment that this equipment and the exhaust gas that does not allow from gas turbine burn in boiler, and the consideration method of operational limit scope is different.In addition, present embodiment reduces steam turbine output in predetermined operational limit scope when gas turbine output sharply descends, cause that with common certain accident state of affairs in service the occasion that gas turbine output sharply descends is an object, the also target of setting gas turbine and steam turbine output in predetermined operational limit scope.In other words, present embodiment is that the safe operation of steam turbine gets involved steam turbine itself, reduces the output of steam turbine itself.