JP2005155349A - Boiler control method following up load variation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent stopping of a boiler caused by followup failure by making generated power follow up a variation in load electric power with excellent responsiveness in a private power generation facility, and also to perform efficient operation by reducing external electric power. <P>SOLUTION: This boiler control method following up the load variation adjusts a power generation amount in the private power generation equipment. Excessive fuel is previously supplied to a fuel supply amount on static characteristics, a turbine bypass valve arranged in a turbine inlet part supplying steam from a boiler is set to have an intermediate opening, and steam pressure is adjusted by operating the turbine bypass valve in contrast with a turbine main steam regulating valve. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a boiler control method capable of causing generated power to follow changes in load power with good responsiveness in a private power generation facility.

FIG. 1 shows a system configuration diagram of a private power generation facility, and load power 42 corresponding to the power consumed in the own factory 41 is received from the generated power 43 generated by the private power generation facility 45 and other power sources such as an electric power company. The more the amount of load power 42 that can be covered by the generated power 43, the more economical the external power 44 can be reduced.

In order to reduce the external power 44, it is necessary to make the generated power 43 follow the change in the load power 42 with good responsiveness, but in the conventional technology, the generated power 43 is stably followed to the change in the load power 42. As shown in FIG. 5, the generated power 43 (broken line) cannot follow the required change in the instantaneous load power 42 (solid line). As a result, the difference between the generated power 43 and the load power 42 becomes large, and the insufficient power is compensated by the external power 44 (shaded portion).

The reason why the generated power cannot follow the change in the load power with good response will be described with reference to the circuit configuration diagram shown in FIG. In the conventional drum type boiler, the steam pressure 1 in the drum is detected, and this is compared with the set value 3 by the controller 2, and the boiler master signal 6 is changed so as to eliminate the deviation. This boiler master signal 6 serves as a command for the amount of fuel and air supplied.

When the load power changes, the steam pressure 1 changes because the amount of steam consumed by the steam turbine changes, but there is a time delay before this change appears. In order to compensate for this time delay, when the steam flow rate 4 in the main steam pipe where the change due to the change in the load power appears earlier than the steam pressure 1 is detected and the steam flow rate 4 changes, the change is met. The amount is added to the boiler master signal 6 in advance by the adder 5. So-called boiler tracking control is performed.

However, even if the fuel and air supply charges are increased / decreased by the boiler master signal 6, it takes time for the generated power to increase / decrease, so that the generated power cannot follow the change in the load power with good responsiveness. In this case, the boiler could be stopped due to excessive supply of fuel and air.

On the other hand, in order to reduce the external power, a method of setting the generated power high is conceivable. However, when the generated power exceeds the load power because the follow-up power is poor, surplus power 47 as shown in FIG. Will occur. Since the surplus power 47 is not allowed for reasons such as disturbance to the transmission system upstream of the external power, the generated power cannot be set high.

Further, as a method of reducing external power, a method of predicting a change in load power and causing the generated power to follow the change in load power is known from Patent Documents 1 and 2, for example. There was a problem that it was difficult to predict well.

JP-A-8-186932 JP 2001-69669 A

  It is an object of the present invention to prevent the boiler from being stopped due to poor tracking and to perform efficient operation by reducing external power by making the generated power follow the change in the load power with good responsiveness in the private power generation equipment. To do.

The present invention has been made as a result of intensive studies in order to solve the above-mentioned problems, and the gist of the present invention is the following contents as described in the claims: (1) Self-following load change A boiler control method for adjusting a power generation amount in a power generation facility,
Supply excess fuel in advance with respect to the static fuel supply amount,
Adjusting the steam pressure by setting an intermediate opening of a turbine bypass valve installed at a turbine inlet for supplying steam from the boiler, and causing the turbine bypass valve to move in the opposite direction to the turbine main steam control valve. A boiler control method that follows a characteristic load change.
(2) Holding a boiler master signal consisting of a deviation between the steam pressure and a set value thereof, and adding a fuel bias amount of a turbine bypass valve specified opening bias set value to the boiler master signal, thereby providing a static fuel supply An excess amount of fuel is supplied in advance with respect to the amount, and by adjusting the steam pressure by the turbine bypass valve by opening the turbine bypass valve,
The turbine bypass valve opening correction amount is obtained by a controller for controlling the turbine bypass valve to an intermediate opening and a function generator for gain adjustment based on opening characteristics, and the opening correction amount is added to the steam flow rate. The boiler control method for following a load change according to claim 1, wherein the opening degree of the turbine bypass valve is corrected.

According to the present invention, in a private power generation facility, the boiler input is made constant with respect to a change in load power, and the generated steam is adjusted to the change in load power by adjusting the steam flow required on the turbine side with the turbine bypass valve. It is possible to follow with good responsiveness. As a result, it is possible to reduce the external power and prevent the generation of surplus power.

Hereinafter, a boiler control method according to an embodiment of the present invention will be described with reference to the drawings.
In the system configuration diagram of the private power generation facility shown in FIG. 1, when a large amount of steam is sent from the boiler 46 to the steam turbine 34 when it is necessary to suddenly increase the generated power of the private power generation facility 45, the steam of the boiler 46 As a result of the pressure 1 being lowered, the generated power cannot be increased. In this case, in order to operate the boiler so that the steam pressure 1 is constant, it is necessary to increase the amount of steam generated by increasing the amount of fuel and air.

  On the contrary, when it is necessary to reduce the generated power suddenly, if the amount of steam sent from the boiler 46 to the steam turbine 34 is decreased, the steam is surplus in the boiler 46 and the steam pressure 1 of the boiler rises. The generated power cannot be reduced. In this case, in order to operate the boiler so that the steam pressure becomes constant, it is necessary to reduce the amount of steam generated by reducing the amount of fuel and air. The boiler master signal 6 is a command for increasing or decreasing the amount of fuel and air.

FIG. 2 is a boiler control system diagram showing an embodiment of the present invention. 3 are the same in name and function, and in FIGS. 1 and 2, steam pressures 1 and 1, steam flow rates 4 and 4, turbine bypass steam flow rates 11 and 11, turbine bypass valve opening degree. 13 and 13 and turbine bypass valves 20 and 20 correspond respectively. The boiler master signal 6 in FIG. 2 is output to the coal feeder 37 and the coal grinder 38 in FIG.

  In FIG. 2, the steam pressure 1 is detected, compared with the set value 3 by the controller 2, and the boiler master signal 23 at the controller outlet is changed so as to eliminate the deviation. Further, when the steam flow rate 4 supplied to the boiler in the main steam pipe is detected and a change occurs in the steam flow rate 4, an amount corresponding to the change is preliminarily added to the boiler master signal 6 by the adder 5. Addition, so-called boiler tracking control is performed.

In order to achieve a mode in which the generated power follows the change in the load power with good responsiveness (hereinafter referred to as a fringe mode), the turbine bypass valve 20 tracks the generated power. In the fringe mode, the boiler master signal 23 on the upstream side is held by the switch 9 on the boiler master signal circuit, and the fuel bias amount of the turbine bypass valve specified opening bias setting value 10 is added to the boiler master signal 24 by the adder 8. Thus, an excessive amount of fuel is supplied in advance with respect to the static fuel supply amount.

Here, the switch 9 operates normally so that b → c and in the fringe mode a → c, and the boiler master signal 23 is held, and the boiler master signal 24 is set to the turbine bypass valve specified opening bias setting value. 10 is added. At this time, the fringe mode is a mode in which, for example, the operator operates when a fringe mode push button (not shown) is turned on.

Although the steam pressure 1 supplied from the boiler rises due to the fuel bias addition described above, the switch 9 holds the boiler master signal 23 on the upstream side, so the boiler master signal 23 is not adjusted by the steam pressure 1, and steam The pressure 1 is compared with the set value 19 in the controller 18, and the boiler pressure control output 51 is output based on the deviation, and the turbine bypass valve 20 is opened to adjust the steam pressure.

  Here, the fuel bias amount of the turbine bypass valve specified opening bias setting value 10 is a fuel bias amount that becomes an intermediate position (intermediate opening) of the opening range with good controllability by the valve opening characteristic of the turbine bypass valve 20. Since it is set, the turbine bypass valve 20 has an intermediate opening. Further, the subtractor 12 subtracts the turbine bypass steam flow rate 11 from the steam flow rate 4 supplied from the boiler, thereby preventing changes in the boiler master signals 23 and 24 due to the change in the steam flow rate 4 due to the opening / closing operation of the turbine bypass valve 20. doing.

A steam flow signal used for power generation is taken out from the output of the subtractor 12 in FIG. In addition, the turbine bypass valve 20 is moved in the opposite direction to the turbine main steam control valve 33 (FIG. 1). As a result, the steam flow rate 4 (power generation steam flow rate + turbine bypass steam flow rate) supplied from the boiler is kept almost constant, and the steam pressure change in the boiler, which is mainly caused by a rapid change in steam usage, is reduced. Since the steam pressure does not exceed the allowable boiler pressure value, the boiler stop can be prevented.

Further, by correcting the opening degree of the turbine bypass valve 20 by the function of the output 51 of the control device 18 that receives the boiler pressure change, the power generation output that can be controlled in the fringe mode with respect to a gradual power generation output change. The range of use can be increased, and high power operation can be performed with less external power.
When a small load change 48 (FIG. 4) occurs, the steam flow rate changes in the steam turbine 34 (FIG. 1) and the steam pressure 1 changes. The steam pressure 1 is adjusted by the controller 18 to adjust the opening of the turbine bypass valve 20. Controlled by Further, in the fringe mode, the switch 16 is switched to the correction side (a → c), the controller 14 for controlling the turbine bypass valve opening 13 to an intermediate opening, and the function generator 15 for gain adjustment based on the opening characteristics. By calculating the opening correction amount of the bypass valve 20 and adding the opening correction amount to the steam flow rate 4 by the adder 17, the opening correction of the turbine bypass valve 20 is performed and the turbine bypass valve 20 is maintained at the intermediate opening. can do. Here, the switch 16 operates normally so that b → c and a → c in the fringe mode, and the opening degree correction is performed.

3 is a set value of the steam pressure, 7 is a switch, 25 is a normal bias amount, 26 is a deaerator, 27 is a water supply pump, 28 is a water supply control valve, 29 is a economizer, 30 is a drum, 31 Is a water wall, 32 is a superheater, 33 is a main steam control valve, 35 is a condenser, 36 is a condensate pump, 39 is a primary air fan, and 40 is a generator.

  FIG. 4 is a load change pattern diagram to which this embodiment is applied. As shown in FIG. 4, the load changes with a small load change width 48, and a high load change rate of 5 to 10% / min is required. Has been.

FIG. 6 is a characteristic diagram showing the follow-up to the load change according to the present embodiment. Here, the relationship between the load change width and the load change rate, and the load change mode targeted by the control according to the present invention will be described. In the conventional technology, when the load change rate is small, for example, about 6 to 7%, and the load change rate is less than 3% / min (low load change rate), control is possible if the load change frequency is low. However, control is not possible when the load change frequency is high. In contrast, in the present invention, control is possible regardless of the load change frequency by the fringe mode, and control is possible even when the load change rate exceeds 3% / min.

As described above, the main feature of the present invention is that the boiler input is fixed with respect to a small load change width at a high load change rate, and the steam amount required on the turbine 34 side is adjusted by the turbine bypass valve 20. Is what you do. In the above description, the water cover 35 is connected to the outlet side of the turbine bypass valve 20. However, instead of the water cover 35, the water cover 35 is connected to a steam accumulator or the like, and the necessary amount is converted into factory process steam from there. If supplied, the steam passing through the turbine bypass valve 20 can be used effectively without wasting it back to water.

It is a control system diagram of the private power generation equipment to which the present invention is applied. It is a control system diagram of boiler master control showing an embodiment of the present invention. It is a control-system figure of boiler master control of a prior art. It is a figure which shows the change pattern of the load electric power to which this invention is applied. It is a figure which shows the followable | trackability of the generated electric power to the load electric power in the past. It is a figure which shows the followable | trackability of the generated electric power to the load electric power by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steam pressure 2 Controller 3 Set value 4 Steam flow supplied from boiler 5 Adder 6 Boiler master signal 7 Switcher 8 Adder 9 Switcher 10 Turbine bypass valve regulation opening bias set value 11 Turbine bypass steam flow rate 12 Subtractor 13 turbine bypass valve opening 14 controller 15 function generator 16 switch 17 adder 18 controller 19 set value 20 turbine bypass valve 23 boiler master signal (steam pressure controller outlet)
24 Boiler master signal (steam flow rate adder exit)
25 Normal-time bias amount 26 Deaerator 27 Water supply pump 28 Water supply control valve 29 Carburizer 30 Drum 31 Water wall 32 Superheater 33 Main steam control valve 34 Steam turbine 35 Condenser 36 Condensate pump 37 Coal feeder 38 Coal Crusher 39 Primary air fan 40 Generator 41 Own factory 42 Load power 43 Generated power 44 External power 45 Private power generation equipment 46 Boiler 47 Surplus power 48 Small load change 49 Reverse characteristic function 50 Steam flow used for power generation 51 Boiler pressure control output

Claims (2)

A boiler control method for adjusting the amount of power generation in a private power generation facility following a load change,
Supply excess fuel in advance with respect to the static fuel supply amount,
Adjusting the steam pressure by setting an intermediate opening of a turbine bypass valve installed at a turbine inlet for supplying steam from the boiler, and causing the turbine bypass valve to move in the opposite direction to the turbine main steam control valve. A boiler control method that follows a characteristic load change. By holding a boiler master signal consisting of a deviation between the steam pressure and its set value, and adding the fuel bias amount of the turbine bypass valve prescribed opening bias set value to the boiler master signal, By supplying excess fuel in advance and adjusting the steam pressure by the turbine bypass valve by opening the turbine bypass valve,
The turbine bypass valve opening correction amount is obtained by a controller for controlling the turbine bypass valve to an intermediate opening and a function generator for gain adjustment based on opening characteristics, and the opening correction amount is added to the steam flow rate. The boiler control method for following a load change according to claim 1, wherein the opening degree of the turbine bypass valve is corrected.

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