JPH0335922Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a boiler steam temperature control device that controls the steam temperature of a boiler to a temperature that corresponds to a turbine load.

Turbines for power generation and the like are operated by steam from the superheater and reheater of the boiler. This steam is supplied to the turbine through steam piping that connects the outlet of the superheater or reheater and the turbine inlet, but the boiler and turbine are generally installed with a considerable distance between them. , the length of the piping becomes longer,
The length will be 60-100m. By the way, in order to supply steam according to the required turbine load, it is necessary to maintain the turbine inlet steam temperature at a predetermined value. Normally, a temperature detector is installed in the section) to constantly monitor the steam temperature.

FIG. 1 is a steam system diagram between a boiler and a turbine.

In the figure, 1 is a boiler, 2 is a superheater provided near the furnace outlet of the boiler 1, 3 is a turbine, and 4 is a steam pipe connecting the outlet of the superheater 2 and the inlet of the turbine 3. 5 is a boiler outlet temperature detector provided at the outlet of the superheater 2, and 6 is a turbine inlet temperature detector provided at the turbine inlet. Steam from the superheater 2 is supplied to the turbine 3 through a steam pipe 4 to drive it.

By the way, in order to supply steam according to the turbine load, it is necessary to maintain the steam temperature at the turbine inlet at a desired value. In order to maintain the steam temperature at a desired value in this manner, it is most desirable to perform necessary control of the boiler based on the temperature detected by the turbine inlet temperature detector 6. However, as mentioned above, the length of the steam pipe 4 between the boiler outlet and the turbine inlet is 60~
Since it reaches 100m, the turbine inlet temperature sensor 6
Even if the boiler is controlled based on the detected temperature, there is a time delay, that is, a response delay, in controlling the temperature at the turbine inlet to a predetermined value due to the length of the steam pipe 4. Therefore, in order to prevent this response delay, boiler steam temperature control has conventionally been performed based on the temperature detected by the boiler outlet temperature detector 5.

FIG. 2 is a block diagram of a conventional boiler steam temperature control device. In the figure, 5 is the same boiler outlet temperature detector as shown in FIG. 1, and 7 is a temperature setting device. The temperature setting in the temperature setting device 7 is based on the steam temperature at the turbine inlet according to the required turbine load, and a certain temperature drop in the steam piping 4, which is determined by taking into account the length of the steam piping 4 and other conditions. It is set by adding the minutes. Therefore, the temperature set by the temperature setting device 7 becomes the boiler outlet steam temperature in accordance with the required turbine load. Reference numeral 8 denotes a temperature regulator which inputs signals from the boiler outlet temperature detector 5 and temperature setting device 7 and outputs a boiler control signal. Various configurations are possible for the temperature controller 8, but for example, it is configured with a comparator 8a that compares the two signals, and a level controller 8b that converts the output of the comparator 8a into a signal convenient for control. be done.
Reference numeral 9 is an automatic/manual switch, which outputs a manual control signal when necessary. Reference numeral 10 denotes an operation unit for operating various devices for changing the steam temperature, and drives these devices in accordance with control signals from the temperature regulator 8.

Now, when the signal from the boiler outlet temperature detector 5 and the signal from the temperature setting device 7 do not match, the temperature regulator 8 outputs a control signal to the operating section 10. The operating section 10 performs necessary operations in response to this control signal, and sets the steam temperature at the boiler outlet to a required temperature value. Various objects can be considered to be controlled by the operation unit 10, such as the amount of fuel supplied to the burner of the boiler, the distribution ratio of the amount of fuel to each stage of the burner, and the flow rate of water in the desuperheater. In this way, the steam temperature at the turbine inlet can be maintained at a specified value, and steam can be supplied in accordance with the required turbine load.

In the conventional boiler steam temperature control device described above, the temperature setting device 7 is set by setting the temperature drop in the steam pipe 4, that is, the temperature difference between the boiler outlet steam temperature and the turbine inlet steam temperature, to a constant value. Ta. However, this temperature difference is not always constant, but changes due to fluctuations in the turbine load, for example. That is, when the turbine load increases, the steam pipe 4
The steam flow rate flowing through the turbine also increases, and as the turbine load decreases, the steam flow rate also decreases. Due to this change in flow rate, the temperature difference also changes by 3 to 5°C. For this reason, for example, if the boiler outlet steam temperature is set to 541°C taking into account the temperature drop in the steam pipe 4, the turbine inlet steam temperature will vary between 538°C and 536°C. Such temperature difference fluctuations occur not only due to turbine load fluctuations but also due to various other causes. When such a temperature difference fluctuates, it is difficult for conventional boiler steam temperature control devices to control the turbine inlet steam temperature to a specified value. However, in recent years, demands for improved thermal efficiency have become increasingly strict, and as a result, the need to maintain the turbine inlet steam temperature at a specified value has also become greater. Therefore, in the conventional boiler steam temperature control device described above, it is necessary to constantly monitor the steam temperature at the turbine inlet, and to correct the boiler outlet temperature set value when this temperature deviates from a specified value. However, automatic steam temperature control cannot be performed with this method, and furthermore, unless a skilled operator carefully adjusts the boiler outlet temperature set value, the steam temperature at the boiler outlet may fluctuate greatly. , there was a risk that a situation would occur in which the boiler and turbine equipment could not be operated safely.

An object of the present invention is to provide a boiler steam temperature control device that can reliably control the turbine inlet steam temperature to a specified value and can perform this control without response delay, while eliminating the above-mentioned conventional drawbacks. It is in.

In order to achieve this objective, the present invention uses a set value of a temperature setting device to set the boiler outlet steam temperature determined based on a predetermined temperature difference between the boiler outlet and the turbine inlet. The difference is subtracted, the deviation between this subtracted value and the signal from the turbine inlet temperature sensor is calculated, this deviation is added to the set value of the temperature setting device, and this added signal and the boiler outlet temperature detection are calculated. The boiler steam temperature is controlled by outputting a control signal based on the signal from the boiler.

The present invention will be explained below based on the embodiment shown in FIG.

FIG. 3 is a block diagram of a boiler steam temperature control device according to an embodiment of the present invention. In the figure, parts that are the same as those shown in FIG. 2 are given the same reference numerals, and explanations thereof will be omitted. 6 is a turbine inlet temperature detector that detects the temperature of the turbine inlet. 7A is a temperature setting device which, like the temperature setting device 7 shown in FIG. 2, sets the boiler outlet temperature to a desired temperature and outputs a signal corresponding to the set temperature. Reference numeral 11 denotes a first computing unit in which a predetermined value (plan base) is set as the temperature difference between the boiler outlet and the turbine inlet according to this temperature difference, and the setting in the temperature setting device 7A A value is input and an operation is performed to subtract the predetermined value from this set value. 12 is a second computing unit that computes the deviation between the turbine inlet temperature detector 6 and the first computing unit 11; 13 is a proportional integrator that proportionally integrates the signal output from the second computing unit 12; This is an adder that adds the output signal of the proportional integrator 13 to the output signal of the temperature setting device 7A.
The output signal of the adder 14 is input to the temperature controller 8.

Next, the operation of this embodiment will be explained. First, the temperature required at the boiler outlet is set in the temperature setting device 7A according to the turbine load. The temperature setting device 7A outputs a signal corresponding to the set temperature. The first computing unit 11 is a temperature setting device 7A.
, and subtracts a predetermined value from the output signal held by the first arithmetic unit 11 itself according to the temperature difference. Therefore, the output signal from the first computing unit 11 has a value corresponding to the turbine inlet temperature obtained by subtracting the predetermined temperature difference from the boiler outlet temperature. The output signal of the first computing unit 11 is input to the second computing unit 12, and the second computing unit 12 combines this output signal with the actual turbine inlet temperature output from the turbine inlet temperature detector 6. The deviation from the corresponding value is calculated. Now, the actual temperature difference between the temperature at the boiler outlet and the temperature at the turbine inlet is determined by the first computing unit 11.
If the temperature difference is equal to the temperature difference set in , the deviation calculated by the second calculation unit 12 becomes 0. On the other hand, if the temperature difference changes due to a change in the turbine load or the like and the actual temperature difference becomes a value different from the temperature difference set in the first calculation unit 11, the second calculation unit 12 A deviation signal is output in accordance with the temperature setting device 7A, and the deviation is added to the output signal of the temperature setting device 7A by an adder 14 via a proportional integrator 13. For example, if the actual temperature difference is 2°C larger than the temperature difference set in the first calculator 11, the deviation calculated in the second calculator 12 will be +2°C, and the adder 14 will calculate the difference by +2°C. A signal corresponding to +2° C. is added to the output signal of the temperature setting device 7A.
On the contrary, if the actual temperature difference is
When the temperature difference is 2° C. smaller than the temperature difference set in , the deviation becomes −2° C., and the adder 14 adds a signal corresponding to the −2° C. deviation to the output signal of the temperature setting device 7A. In the end, the signal output from the adder 14 is the temperature at the boiler outlet necessary to obtain the temperature at the turbine inlet corresponding to the turbine load, regardless of any fluctuation in the temperature difference between the boiler outlet and the turbine inlet. The signal will be generated accordingly. This adder 1
The output signal of 4 is input to the temperature controller 8, and a deviation signal from the output signal of the boiler outlet temperature detector 5, which is also input to the temperature controller 8, is calculated. The outlet temperature is controlled to the temperature set in the temperature setting device 7A.

In this way, in this embodiment, the first arithmetic unit has
Set a value according to a predetermined temperature difference, subtract the value according to the temperature difference from the set value of the temperature setting device that sets the temperature at the boiler outlet, and compare the value obtained by subtraction with the turbine inlet. The deviation from the value corresponding to the temperature is calculated, this deviation is added to the setting value of the temperature setting device, and the operating unit is operated based on the deviation between the value obtained by the addition and the value corresponding to the detected boiler outlet temperature. Since the boiler outlet temperature is controlled by operation, the turbine inlet temperature can be reliably controlled to the required temperature regardless of fluctuations in temperature difference, and the temperature at the boiler outlet can be detected. Since the temperature at the outlet of the boiler is controlled, there is no response delay and responsiveness equivalent to that of the conventional system can be obtained.

As described above, in the present invention, a value corresponding to a predetermined temperature difference is subtracted from the set value of the temperature setting device that sets the temperature at the boiler outlet, and this subtracted value and the temperature at the turbine inlet are The deviation from the value corresponding to the temperature is calculated, this deviation is added to the set value of the temperature setting device, and the temperature at the boiler outlet is determined based on this added value and the value corresponding to the temperature at the boiler outlet. Since the control signal is output, the temperature at the turbine inlet can be reliably controlled to a specified value, and this can be done without response delay.

[Brief explanation of the drawing]

FIG. 1 is a steam system diagram between a boiler and a turbine, FIG. 2 is a block diagram of a conventional boiler steam temperature control device, and FIG. 3 is a block diagram of a boiler steam temperature control device according to an embodiment of the present invention. 5... Boiler outlet temperature detector, 6... Turbine inlet temperature detector, 7A... Temperature setter, 8... Temperature controller, 10... Operating unit, 11... First computing unit, 12... Second arithmetic unit, 14...adder.

Claims (1)

[Scope of utility model registration request] A boiler, a turbine driven by steam from the boiler, and piping for sending steam from the boiler to the turbine, wherein a predetermined distance between the boiler outlet of the boiler and the turbine inlet of the turbine is provided. A temperature setting device that sets a boiler outlet temperature determined based on the temperature difference, a first computing unit that subtracts the temperature difference from a set value set in the temperature setting device, and a temperature detector that detects the temperature at the turbine inlet. a first temperature sensor that calculates the deviation between the detected value of the first temperature sensor and the value calculated by the first calculation unit; an adder that adds the calculated deviation and the set value of the temperature setting device; a second temperature detector that detects the temperature at the boiler outlet; and the detector of the second temperature detector and the adder. What is claimed is: 1. A boiler steam temperature control device, comprising: a control section that controls boiler steam temperature based on the determined value.