JPH0711300Y2 - Reheat steam temperature controller for starting boiler equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a reheated steam temperature control device for a boiler device, which controls the temperature of reheated steam supplied to a turbine in the boiler device.

[Prior Art] In recent years, in order to operate a thermal power plant with high efficiency,
The plant specifications for start-stop operation every day are increasing.
In such daily start-stop operation, it is necessary to perform unit start-up with a short start-up time.

By the way, at the time of starting the unit, the thermal stress of the turbine increases, so that there is a problem that the life of the turbine is shortened.
In particular, in order to prevent shortening the life of the medium-pressure turbine rotor,
Improvement of reheat steam temperature characteristics has been demanded.

Conventionally, at the time of boiler startup, when steam is supplied to the medium-pressure turbine and this is rotated at a specified speed and is also combined with the high-pressure turbine (ventilation-combined), the RH water spray (reheat) is used for steam temperature control. In some cases, measures such as steam water spray) and combustion control were adopted.

[Problems to be solved by the invention] However, unless the RH water spray is used in a state where the reheat steam flow rate is secured to some extent, there is a problem in relation to the water contact, and it cannot be used at the time of ventilation-combination. . Further, the combustion amount suppressing means can lower the gas temperature and can control the steam temperature to some extent, but the boiler evaporation amount is required to maintain the ventilation pressure to the turbine. In order to obtain the quantity, there is a limit to the suppression of the combustion quantity, and practically, there was almost no control margin, and it was difficult to carry out the required control. As described above, conventionally, the reheat steam temperature control does not have a concretely effective means, and is in a state close to non-control.

The present invention has been made in view of the above circumstances, and an object thereof is to be able to control the reheat steam temperature at the time of boiler startup to an appropriate temperature, and to reduce the thermal stress of the turbine to reduce the thermal stress. Another object of the present invention is to provide a reheat steam temperature control device for a boiler device, which can prevent a decrease in life.

[Means for Solving the Problems]

In order to achieve the above object, the present invention detects an air supply port provided in a wind box downstream of a boiler furnace, a damper for adjusting the amount of air supplied to the air supply port, and a reheat steam temperature. A temperature detecting device, a temperature setting device for setting a required reheat steam temperature, a calculating means for calculating a deviation between a temperature detected by the temperature detecting device and a temperature set by the temperature setting device, and this calculation Air amount determining means for determining the air amount for reheat steam temperature control independently of the air amount supplied to the wind box based on the deviation obtained by the means, and the air determined by this air amount determining means It is characterized in that a start-up reheated steam temperature control device of the boiler device is constituted by a damper control means for controlling the damper based on the amount.

[Action]

At the time of starting the boiler, the reheat steam temperature is detected by the temperature detecting device, and the deviation between the detected temperature and the required reheat steam temperature preset in the temperature setting device is calculated by the calculating means. An air amount determining means such as a function generator obtains an air amount corresponding to the calculated deviation. The amount of air thus obtained is an amount of air independently obtained, completely separate from the amount of air supplied to the wind box required for combustion in the boiler furnace. The damper control means controls the damper so as to supply the required air amount to the air supply port.

〔Example〕

The present invention will be described below with reference to the embodiments shown in FIGS. 1 and 2.

FIG. 1 is an air supply system diagram of a boiler device according to an embodiment of the present invention. In the figure, 1 is a furnace of a boiler apparatus, 2 is a window box for supplying air to a burner apparatus, and 3 is an NO port arranged on the downstream side of the window box 2. this
NO port 3 is a port used for low NO _x control in the two-stage combustion system. Reference numeral 4 is an NO port damper for adjusting the flow rate of air supplied to the NO port 3, 5 is an NO port air flow rate detector for detecting the flow rate of air supplied to the NO port 3, and outputting a signal in accordance therewith, 6 is It is an air flow rate detector that detects the flow rate of air supplied to the window box 2 and the NO port 3 and outputs a signal corresponding to this. In this embodiment, when the boiler apparatus is started, the opening of the NO port damper 4 is appropriately controlled to supply an appropriate amount of air from the NO port 3 into the furnace 1, and the air is burned at high temperature in the furnace 1. The reheated steam temperature is controlled by mixing it with gas. The control apparatus of this embodiment is shown in the following figure.

FIG. 2 is a system diagram of a reheat steam temperature controller according to an embodiment of the present invention. In the figure, the same parts as those shown in FIG. 1 are designated by the same reference numerals. A reheated steam temperature detector 7 measures the reheated steam temperature and outputs a signal according to the measured value. Reference numeral 8 is a reheat steam temperature setting device that can arbitrarily set a reheat steam temperature suitable for reheating and outputs a signal according to the set temperature. 9 is a reheated steam temperature detector 7
, A subtracter for calculating a deviation between the signal of the reheat steam temperature setting device 8 and a function generator 10 for obtaining an air flow rate corresponding to the output signal of the subtractor 9 and outputting a signal in accordance therewith. Is
It is a subtractor that calculates the difference between the output signal of the NO port air flow rate detector 5 and the output signal of the function generator 10.

12 is an air flow rate command signal transmitter that outputs a signal according to the flow rate of air required for combustion, 13 is an air flow rate command signal transmitter 12
Function generator for obtaining the air flow rate to be sent to the NO port 3 in accordance with the command air flow rate of No. 14, 14 is an adder for adding the output signal of the function generator 13 and the output signal of the subtractor 11, and 15 is the NO port It is an automatic manual switching device that switches between automatic control for controlling the damper 4 by the output signal of the adder 14 and manual adjustment for manual adjustment.

16 is an adder for adding the output signal of the air flow command signal transmitter 12 and the output signal of the subtractor 11, 17 is an air flow signal transmitter for outputting a signal according to a predetermined air flow, and 18 is an adder 16
Of the output signals of the air flow rate signal transmitter 17 and the output signal of the air flow rate signal transmitter 17, which is the high signal selector. 19 indicates the deviation between the output signal of the high signal selector 18 and the detection signal of the air flow rate detector 6. A subtractor for calculation, 20 is an automatic manual switching device, and 21 is a moving blade of a forced draft fan. By controlling the moving blade 21, the amount of air supplied from the forced draft fan can be adjusted.

Next, the operation of this embodiment will be described. Since the amount of combustion gas is small and the combustion gas temperature is low at boiler startup, the air injected from the NO port is more significantly tempered than it contributes to the two-stage combustion effect during normal operation. Contribute to the effect. In this embodiment, paying attention to this point, the reheat steam temperature is controlled.
First, when the boiler device is started up, the reheated steam temperature optimum for starting up is set in the reheated steam temperature setter 8. Next, the set reheated steam temperature and the reheated steam temperature detected by the reheated steam temperature detector 7 are input to the subtractor 9 to calculate the deviation between the two temperatures. The calculated reheat steam temperature deviation signal is a function generator
The value is input to the function generator 10, and the function generator 10 obtains a preset value corresponding to the input deviation signal. This value corresponds to the air flow rate that needs to be increased or decreased to bring the reheat steam temperature to the set temperature. That is, the function generator
The signal output from 10 is an air flow rate command signal. This air flow rate command signal is input to the subtractor 11, and the deviation from the signal corresponding to the air flow rate supplied to the NO port 3 (the signal detected by the NO port air flow rate detector 5) is calculated. On the other hand, the air flow rate command signal transmitter 12 outputs an air flow rate command signal required for combustion. This signal is input to the function generator 13, and the function generator 13 determines the air flow rate that should contribute to the combustion reaction that is input from the NO port 3 in accordance with the commanded air flow rate. That is, the signal output from the function generator 13 is the NO port flow rate signal required for combustion. The output signal of the function generator 13 is added in the adder 14 to the output signal of the subtractor 11, that is, a signal corresponding to the air flow rate that does not contribute to combustion but contributes to the rise and fall of the reheat steam temperature. As a result, the signal output from the adder 14 becomes a signal corresponding to the air flow rate to be supplied to the NO port 3 necessary for combustion and control. The opening of the NO port damper 4 is controlled according to the signal input through the automatic manual switcher 15 to allow the required amount of air to flow into the NO port 3.

On the other hand, the total air flow rate to be supplied to the window box 2 and the NO port 3 is controlled as follows. That is, the air flow rate command signal for combustion from the air flow rate command signal transmitter 12 is added to the output signal of the subtractor 11 by the adder 16. Therefore, the adder 16 outputs a command signal according to the total air flow rate required for combustion and control. This command signal is the high signal selector 18 (the high signal selector 18 will be described later).
And is input to the subtractor 19. At the same time, the detection signal detected by the air flow rate detector 6 is also input to the subtractor 19,
At 19, the deviation between the input detection signal and the command signal is calculated. Therefore, the subtractor 19 outputs a deviation signal regarding the total air flow rate, and the moving blades of the forced draft fan are drive-controlled in a direction to eliminate this deviation according to the deviation signal. Here, the signal generator 17 and the high signal selector 18 will be described. Generally, it is necessary to secure a predetermined amount of gas in the boiler furnace, and if this amount is insufficient, the atmospheric pressure outside may damage the furnace wall, flue, etc. Since the signal generator 17 provides an air flow rate for ensuring a predetermined gas amount, it outputs a signal corresponding to this. High signal selector
When the output signal of the adder 16 is a signal of a magnitude that cannot secure the predetermined amount of gas, 18 selects the signal of the signal generator 17 to prevent the damage.

FIG. 3 is a characteristic diagram of the reheat steam temperature with respect to the air flow rate. As is clear from the figure, the reheat steam temperature is NO port 3
It decreases linearly as the air flow rate increases.
That is, as the amount of air mixed in the hot gas is increased, the hot gas is cooled by that amount and the reheat steam temperature is lowered. Conversely, when the amount of mixed air is decreased, the reheat steam temperature rises. Thus, the reheat steam temperature can be effectively controlled.

As described above, in this embodiment, the flow rate of the air mixed in the high temperature gas from the NO port is controlled to an appropriate temperature based on the deviation between the reheat steam temperature set to the optimum value and the actual reheat steam temperature. Therefore, the reheat steam temperature can be controlled in a range where the RH spray or the like cannot be used at the time of start-up, and the thermal stress of the turbine can be reduced to prevent the life of the turbine from being shortened. Further, the start-up time can be shortened as compared with the start-up in which the temperature is gradually increased in an uncontrolled state in order to prevent the thermal stress of the turbine from increasing. Further, since the existing device such as the NO port is used, the control device can be configured easily and at low cost.

Note that it is also possible to use together with the control device of the above-mentioned embodiment, a means for injecting the steam bypassed from the boiler to the condenser into the reheater steam outlet to control the reheated steam temperature. Further, without using the NO port, a port for controlling the reheat steam temperature and a damper attached to the port can be separately provided.

[Effect of device]

As described above, in the present invention, based on the deviation between the reheat steam temperature set to the optimum value and the actual reheat steam temperature,
Since the flow rate of the air mixed in the high temperature gas from the upper port of the windbox in the boiler furnace is controlled, the reheat steam temperature at startup can be controlled appropriately, which in turn reduces the thermal stress of the turbine It is possible to prevent a decrease in life. It is also possible to shorten the startup time.

[Brief description of drawings]

1 is an air supply system diagram of a boiler device according to an embodiment of the present invention, FIG. 2 is a system diagram of a control device according to an embodiment of the present invention, and FIG. 3 is a characteristic diagram of reheat steam temperature with respect to air flow rate. Is. 2 ... Wind box, 3 ... NO port, 4 ... NO port damper, 5 ... NO port Air flow rate detector, 6 ... Air flow rate detector, 7 ... Reheated steam temperature detector, 8 ... Reheat steam temperature setter, 9,11,19 …… Subtractor, 10,13 …… Function generator, 14,16 …… Adder, 21 …… Indented blower blade.

Claims (1)

[Scope of utility model registration request] 1. An air supply port provided downstream of a wind box of a boiler furnace, a damper for adjusting an amount of air supplied to the air supply port, a temperature detection device for detecting a reheated steam temperature, and a required device. A temperature setting device for setting the reheat steam temperature, a calculation means for calculating the deviation between the temperature detected by the temperature detection device and the temperature set by the temperature setting device, and the deviation obtained by this calculation means. Based on the amount of air supplied to the wind box based on the air amount determination means for determining the amount of air for reheat steam temperature control, and the damper based on the amount of air determined by this air amount determination means A reheat steam temperature control device at startup of a boiler device, characterized in that a damper control means for controlling is provided.