JPH0484002A - Steam temperature controller - Google Patents

Abstract

PURPOSE:To raise the response performance against a load variation by comparing outlet temperature target value signals for water wall third stage, fourth stage, and flue evaporator and the sensed temperature signals to obtain deviation signals and obtaining operation signals by carrying out proportional and differential control calculations and adding the signal given by addition and composition of the operation signals and the fuel feedforward signals to obtain fuel signals. CONSTITUTION:By pressure sensors 1A-1C, temperature sensors 2A-2C the outlet pressures and outlet temperatures of third stage and fourth stage of water wall and flue evaporator are detected. The outlet pressure signals 3A-3C of pressure sensors 1A-1C are inputted to function generators 5A-5C to obtain temperature target signals 4A-4C. To comparators 8A-8C function temperature target value signals 4A-4C and temperature detection value signals 6A-6C from temperature sensors 2A-2C are inputted to obtain deviation signals 7A-7C. The deviation signals 7A-7C are inputted to control and adjustment devices 10A-10C to carry out proportional and differential control calculations to obtain operational value signals 9A-9C. In an adder 20 the signal by addition and composition of respective operation value signals 9A-9C and fuel feedforward signal 18 are added and composed to obtain fuel signal 19 and steam temperature is controlled.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a device for controlling the steam temperature of a boiler plant that burns fuel and generates steam using the combustion heat, and in particular, the present invention relates to a device for controlling steam temperature in a boiler plant that burns fuel and generates steam using the heat of combustion. The present invention relates to a steam temperature control device that performs control reliably and prevents disturbances from being caused to a plant even when the temperature is high.

[Prior Art] FIG. 2 is a block diagram showing an example of the configuration of a steam temperature control device for a conventional boiler plant of this type.

Generally, in a boiler plant, steam temperature is controlled by fuel, and pressure is controlled by feed water flow rate. That is, in FIG. 2, a pressure detector (not shown) detects the outlet pressure (P, , ) 1 of the boiler plant's water oar.
1 is detected and inputted to the function generator (F,) 12 to set the temperature target value (T, . . . ) 13.

Next, this set temperature target value (T,,,) 13,
A temperature deviation signal (T eal WWT, i) from the water wall outlet temperature (W W r=, ) 14 detected by a temperature detector (not shown) is obtained. Then, the obtained temperature deviation signal (T, , -WWT, , ) is input to the control regulator 15, where a proportional control calculation is performed to obtain a manipulated variable signal, and furthermore, a fuel feed is applied to this manipulated variable signal. The forward signals 16 are added and combined to obtain a fuel signal 17 corresponding to the steam temperature, which is the final manipulated variable signal, and the steam temperature is controlled based on this fuel signal 17.

By the way, in such a steam temperature control device for a boiler plant, when the boiler is operating, steam without moisture normally flows in a high load range. On the other hand, as the load is lowered, the steam becomes moist and water and steam begin to separate, eventually reaching a saturated state. In such a situation, even if the steam pressure changes, the temperature will not change above the saturation temperature. Therefore, with the conventional temperature control method using pressure detection, the water owl outlet temperature will not fluctuate beyond a certain value, so the steam It becomes difficult to control the temperature.

[Problem to be solved by the invention] As described above, in the conventional steam temperature control device, when the water wall approaches the saturated state, even if the steam pressure changes, the temperature does not change beyond the saturation temperature. Temperature control becomes difficult.

This is because the outlet temperature of the water all does not change beyond the saturation temperature, making it difficult to control the steam temperature by changing the outlet pressure of the water all, resulting in an uncontrolled state.

Furthermore, since there is a delay in the heat exchanger of the boiler plant, the response to sudden load changes is delayed, and it takes time to reach a stable state.

Furthermore, in an uncontrolled state, the fuel signal will cause a disturbance to the boiler plant.

The present invention was made to solve the above-mentioned problems, and its purpose is to reliably control the steam temperature so as not to cause any disturbance to the plant even when the water wall approaches saturation. Extremely reliable steam temperature control that can compensate for heat exchanger delays and increase responsiveness to sudden load fluctuations, and can also quickly supply fuel depending on the boiler condition. The goal is to provide equipment.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a device for controlling the steam temperature of a boiler plant that burns fuel and generates steam using the combustion heat. The 1st and 2nd sections are divided into two, and the 3rd and 4th stages of the water wall and the outlet pressure of the flue evaporator are detected individually. and a third pressure detection means, 3 stages and 4 stages of water oars,
and a first one which separately detects the outlet temperature of the flue evaporator. Second. and a third temperature detection means; Second
．． and the third pressure detecting means, respectively, and individually generate temperature target value signals corresponding to the outlet pressure signals. second and third function generating means; Second. and the temperature target value signal from the third function generating means and the first, second . and a temperature detection value signal from the third temperature detection means, respectively, and compare the two and output the deviation signals respectively. and a third comparison means, and a first. The first means inputs the deviation signals from the second and third comparison means individually, performs proportional/derivative control calculations on the deviation signals, and outputs the manipulated variable signals respectively. Second. and a third control adjustment means; Second.
and an adding means for adding and synthesizing the respective manipulated variable signals from the third control adjustment means and the fuel feedforward signal and outputting a fuel signal that is the final manipulated variable signal. are doing.

[Operations] Therefore, in the steam temperature control device of the present invention, the outlet pressures of the third and fourth stages of the water owl and the flue evaporator are individually detected, and and the outlet temperature of the flue evaporator are individually detected, and the temperature target value signal corresponding to each outlet pressure signal is compared with each detected temperature value signal to obtain a deviation signal thereof, respectively, Proportional and differential control calculations are performed on each of these deviation signals to obtain individual manipulated variable signals, and a signal obtained by adding and synthesizing each of these manipulated variable signals and a fuel feedforward signal are added and synthesized. , a fuel signal, which is the final manipulated variable signal, is obtained, and the steam temperature is controlled based on this fuel signal.

Therefore, by providing a pressure detection point at the outlet of the flue evaporator in addition to the outlet of the water all, even if the water all approaches saturation, control can be performed at the flue evaporator. can. Furthermore, by dividing the water oar into two stages, it is possible to provide feedback closer to the superheater, allowing for faster fuel injection. Furthermore, by adding a differential operation to the control regulator, it becomes possible to correct the delay of the heat exchanger, and the responsiveness to sudden load changes can be significantly improved.

[Embodiment] In the present invention, the pressure detection points in the boiler plant are set to three points: the 3rd stage outlet of the water aller, the 4th stage outlet, and the flue evaporator outlet, and the operation of the control adjustment means is proportional operation. By adding a differential operation, adding and synthesizing the manipulated variable signals corresponding to the three points obtained by each control adjustment means, and adding and synthesizing the fuel feedforward signal to this additively synthesized signal, the final manipulated variable signal is obtained. The fuel signal obtained is as follows.

Hereinafter, an embodiment of the present invention based on the above concept will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an example of the overall configuration of a steam temperature control device for a boiler plant according to the present invention.

That is, the steam temperature control device of this embodiment divides the water wall of the boiler plant into two parts, and as shown in FIG. Second. and a third pressure detector IA, IB,
IC and 1st. Second. and third temperature detector 2A, 2
B, 2C, 1st degree, 2nd degree. and third function generator 5A
, 5B, 5C, and the first. Second. and third comparator 8A
, 8B.

8C and 1st. Second. and a third control regulator 10A,
It consists of an IOB, an IOC, and an adder 20.

Here, the first. Second. and a third pressure detector LA, I
B, IC is a 3-stage waterall.

The outlet pressures of the four stages and the flue evaporator are individually detected.

Also, 1st. Second. and third temperature detectors 2A, 2B
, 2C is a 3-stage waterall.

The temperature at the outlet of the four stages and the flue evaporator are individually detected.

Furthermore, the first. Second. and a third function generator 5A, 5
B, 5C are the first. Second. and a third pressure sensor IA
, IB, outlet pressure signal 3A from IC (WW3 P)
, 3B (WW4P), and 3C (EVA, P) are input individually, and temperature target value signals 4A (T, , , A) corresponding to the outlet pressure signals 3A, 3B, and 3C; 4 B
(T,,,B).

4C (T, , C) are generated individually.

On the other hand, the first. Second. and a third comparator 8A.

8B and 8C are the first. Second. and a third function generator 5
Temperature target value signal 4A from A, 5B, 5C.

4B, 4C, and 1st. Second. and third temperature sensor 2
Temperature detection value signal 6A (WW3) from A, 2B, 2C
, 6B (WW4), and 6C (EVAP) are input individually, and the deviation signal 7A (T,
,,A-WW3),7B(T,,,B-WW4)
7C (T, , C-EVAP) are output individually.

Also, 1st. Second. and a third control regulator 10A
1. OB, 1.0C is the 1st. Second. and deviation signals 7A, 7B, '7C from third comparators 8A, 8B, 8C.
are input individually, and the deviation signals 7A, 7B, 7
Proportional and differential control calculations are performed on C, and the manipulated variable signal 9
A, 9B, and 9C are output individually.

Further, the adder 20 includes the first . Second. and each manipulated variable signal 9A from the third control regulator 10A, IOB, and IOC.
, 9B, and 9C, and the fuel feedforward signal 18, and output one fuel signal as the final manipulated variable signal.

Next, the operation of the steam temperature control device for a boiler plant of this embodiment configured as above will be explained.

In FIG. 1, 1. Second. and the third pressure detector IA, IB, IC, three stages of water all, four stages
The stage and flue evaporator outlet pressures are each detected separately. Also, 1st. Second and third temperature detector 2A
, 2B, 2C, 3rd and 4th stage of water oar,
and the flue evaporator outlet temperature are each individually detected. Furthermore, the first. Second. and third function generator 5A
.

5B and 5C include the first. Second. and outlet pressure signal 3A (WW3
P), 3B (WW4P), and 3C (EVApP) are input individually, and the outlet pressure signals 3A, 3B, and 3
Temperature target value signal 4A (T,,,A), 4 corresponding to C
B (T, , , B)4C(T, , , C1 are obtained individually).

Next, the first. Second. and a third comparator 8A.

8B and 8C have the 1st. Second. and temperature target value signals 4A, 4B, 4 from third function generators 5A, 5B, 5C.
C and 1st. Second. and third temperature detectors 2A, 2B
, temperature detection value signal from 2C 6A (WW3), 6B
(WW, I) and 6C (EVAP) are input individually, and the deviation signal 7A (T,
,,A-WWF),7B (T,,,B-WW4),
7C(T, , C-EVAP) are obtained individually.

Also, 1st. Second. and a third control regulator 10A, I
For OB and IOC, 1. Second. and third comparator 8
Deviation signals 7A, 7B, and 7C from A, 8B, and 8C are input individually, and proportional/differential control calculations are performed on these deviation signals 7A, 7B, and 7C, and the manipulated variable signal 9A is
, 9B.

9C are obtained individually. Further, in the adder 20, the first . Second. and a third control regulator 10A, IO
B, ], each manipulated variable signal 9A, 9B obtained by OC,
The signal obtained by adding and combining 9C and the fuel feed forward signal 18 are added and combined to obtain a fuel signal 19 which is the final manipulated variable signal, and the steam temperature is controlled based on this fuel signal 19. Become.

In this case, each control regulator 10A, IOB.

10C has a differential operation added in addition to the proportional operation, so if the variation becomes large due to the differential operation with respect to the delay of the heat exchanger of the boiler plant, the manipulated variable signals 9A, 9B,
Since 9C is greatly changed, a predictive effect will be exerted. As a result, the manipulated variable signal 9A is generated in advance of the delayed response of the heat exchanger.

Since 9B and 9C are output, response delay can be corrected.

Furthermore, when the water-all approaches the saturated region, the steam in the water-all stage begins to become moist, and the temperature no longer changes above the saturation temperature.

Therefore, even if the set temperature changes due to pressure fluctuations, a temperature signal that accurately indicates the state of the boiler cannot be detected. For this reason, normally the fuel side would be in an uncontrolled state, causing disturbance to the boiler plant, but in the configuration of this example, the outlet pressure of the flue evaporator is also detected, and the Yes, 3-point manipulated variable signals 9A, 9B, 9
Since C is added, there is no need to consider the influence of saturation.

Furthermore, since the water wall is divided into two parts, and the flue evaporator is divided into three parts, it is possible to feed back the temperature at a position closer to the superheater. can also give an early fuel signal.

As described above, the steam temperature control device of this embodiment divides the water allergy of the boiler plant into two parts, and the first part separately detects the outlet pressures of the third stage and fourth stage of the water all, and the flue evaporator. Second. and third pressure detectors IA, IB, IC, and the first, second, and third pressure detectors that individually detect the outlet temperatures of the third and fourth stages of the water wall and the flue evaporator. and third temperature detectors 2A, 2B, 2C
And the first. Second. and a third pressure detector IA.

Outlet pressure signals 3A, 3B, and 3C from IB and IC are input individually, and this outlet pressure signal 3A.

The first . Second. and third function generators 5A, 5B, 5C; and temperature target value signal 4A from third function generator 5A, 5B, 5C.
, 4B, 4C, 1st degree, 2nd degree. and temperature detection value signals 6A, 6B, 6 from third temperature detectors 2A, 2B, 2C.
The first, second, . and third comparators 8A, 8B, 8C; Second. and third comparators 8A, 8B.

Deviation signals 7A, 7B, and 7C from 8C are input individually, and proportional and
The first and second sections perform differential control calculations and individually output manipulated variable signals 9A, 9B, and 9C, respectively. and a third control regulator 10A, IOB.

10C and the 1st. Second. and a third control regulator 10A
, IOB, and each manipulated variable signal 9A from IOC.

It is composed of an adder 20 that adds and combines signals 9B and 9C and a fuel feedforward signal 18, and outputs a fuel signal 19 which is a final manipulated variable signal.

Therefore, the following effects can be obtained.

(a) The number of pressure detection points has been increased to three, that is, in addition to the 3rd and 4th stage exits of the water allergen, we have also installed one at the outlet of the flue evaporator, so that the water allar is nearing saturation. Also, it becomes possible to reliably control the steam temperature in the flue evaporator section.

(b) Since the water all is divided into two stages, it is possible to feed back closer to the superheater, so depending on the boiler condition, the fuel signal 19 can be accelerated and fuel can be added earlier. becomes.

(c) Since the control regulators 10A, IOB, and IOC are provided with differential operation in addition to proportional operation, it is possible to compensate for the delay in the heat exchanger of the boiler plant.
It is possible to significantly improve responsiveness to sudden load fluctuations, etc.

[Effects of the Invention] As explained above, according to the present invention, the water wall of a boiler plant that burns fuel and generates steam using the combustion heat is divided into two parts, and the three-stage water wall is divided into three stages.
The outlet pressures of the 4th stage and the flue evaporator are individually detected, and the outlet temperatures of the 3rd stage, the 4th stage of the water wall, and the flue evaporator are individually detected, and the output pressure signal is The corresponding temperature target value signal and each temperature detection value signal are compared to obtain their respective deviation signals, and proportional/derivative control calculations are performed on each deviation signal to obtain the manipulated variable signals respectively. Furthermore, the signal obtained by adding and synthesizing each of these manipulated variable signals and the fuel feedforward signal are added and synthesized to obtain the final manipulated variable signal, which is the fuel signal, so that the water all is in a saturated state. It is possible to reliably control the steam temperature so as not to cause any disturbance to the plant, even if the steam temperature approaches the boiler. It is possible to provide an extremely reliable steam temperature control device that can perform early fuel injection depending on the state of the steam.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a steam temperature control device according to the present invention, and FIG. 2 is a block diagram showing an example of the configuration of a conventional steam temperature control device. IA, IB, IC... 1st. Second. Third pressure detector, 2A, 2B, 2C...first. Second. Third temperature sensor, 3A, 3B, 3C... Outlet pressure signal, 4A, 4B
, 4C...Temperature target value signal, 5A, 5B. 5C... 1st. Second. Third function generator, 6A. 6B, 6C-... Temperature detection value signal, 7A, 7B, 7C...
... Deviation signal, 8A, 8B, 8C... 1st. 2nd ° Third comparator, 9A, 9B, 9C... manipulated variable signal, 10
A, IOB, IOC... 1st. Second. third control regulator, 11... outlet pressure of the water wall, 12...
・Function generator, 13... Temperature target value, 14... Water wool outlet temperature, 15... Control regulator, 16.
...Fuel feedforward signal, 17...Fuel signal, 18...Fuel feedforward signal, 19...
Fuel signal, 20...adder. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Scope of Claims] A device for controlling the steam temperature of a boiler plant that burns fuel and generates steam using the combustion heat, comprising: dividing the water wall of the boiler plant into two, and dividing the water wall into three stages and four stages. , and first, second, and third pressure detection means for individually detecting outlet pressures of the flue evaporator, and detecting outlet temperatures of the third and fourth stages of the water wall and the flue evaporator, respectively The outlet pressure signals from the first, second, and third temperature detection means that are detected individually and the first, second, and third pressure detection means are individually inputted, and the output pressure signals are applied to the output pressure signals. The first one generates the corresponding temperature target value signals individually.
, second, and third function generating means; and temperature target value signals from the first, second, and third function generating means and temperature target value signals from the first, second, and third temperature detecting means. first, second, and third comparison means that individually input the detected temperature value signal, compare the two, and individually output the deviation signals thereof; Input the deviation signals from the comparison means separately, and calculate the proportional and
first, second, and third control adjustment means that perform differential control calculations and individually output manipulated variable signals; and each manipulated variable signal from the first, second, and third control adjustment means. 1. A steam temperature control device comprising: an adding means for adding and combining an additively combined signal and a fuel feedforward signal and outputting a fuel signal that is a final manipulated variable signal.