JPS5981401A - Temperature controller for economizer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application] The present invention relates to a temperature control device for an economizer, and in particular, to a temperature control device for an economizer, which sets the temperature of the economizer outlet feed water by adjusting the economizer recirculation flow ji'a-. The present invention relates to a temperature control device for a fuel economizer that maintains the temperature at a certain temperature.

[Prior art]

First, the overall schematic configuration of an exhaust heat recovery type combined power generation plant suitable for carrying out the present invention is shown in Figure 1, pW! 3 Simply state.

- First, fuel is supplied to the combustor 4 by the gas turbine fuel flow control valve 3 and is combusted. The expanded gas is thereby sent to a gas turbine 1, which drives two generators.

The gas discharged from the gas turbine 1 is transferred to the exhaust gas duct 5.
It passes through an exhaust heat recovery boiler consisting of a superheater 6, an evaporator 7, and an economizer 8, and is discharged to the outside.

On the other hand, the flow rate of water supplied from the condenser 36 is adjusted by the condenser water level control valve 16, and the water supplied from the low pressure feed water heater 3
5, the water is supplied to deaeration a14.

The water that has been subjected to steam and water separation in the deaerator 14 is heated by a boiler feed water pump (BFP) 13, the flow 1 is regulated by the feed water flow rate control valve 12, and the water is heated by the energy saver 8. While performing the exchange, part of the water is supplied to the drum 9, and the depleted water is degassed through all of the recirculation deaerator recovery control valve 10 of the economizer 8 as a recirculation flow rate to prevent steaming of the economizer 8. A portion of it is also collected into the condenser 36 via the economizer recirculation condenser recovery valve 11 .

The water supplied to the drum 9 is converted into steam in the evaporator 7, and the steam inside the drum is transferred to the superheater 6 and becomes superheated steam.
The flow rate is adjusted by the load limiter 19 and vented to the steam turbine 21, thereby driving the generator 22.

When the main steam pressure becomes excessive, a portion of the steam passes through the turbine bypass valve 15, is cooled in the attemperator 20, and then is recovered to the condenser 36. The condenser 36, Ω water, is circulated through a similar route.

As will be described later, the control device 40 of the exhaust heat recovery type combined power generation plant includes an input device 38 that takes in signals from each transmitter such as temperature and pressure as input, and performs all various control calculations using these inputs. It is composed of an arithmetic unit 39 that executes the execution, and an output device f37 that outputs the result.

The control performed by the control device 40 is as follows.

(1) Main steam flow rate transmitter 30, drum water level generator 23
, the energy saving recirculation flow rate transmitter 25, the feed water flow rate transmitter 29, and the drum level control which inputs signals from the control unit $ and outputs them to the feed water flow control valve 12 to control this.

(2) All signals from the drum pressure transmitter 41, economizer outlet water supply temperature transmitter 24, and economizer recirculation flow rate transmitter 25 are input, and control calculations are performed to recover the economizer recirculation condenser. Economizer circulation flow rate control that outputs to valve 11 and controls it.

(3) Ammonia control where the signal from the NOX concentration transmitter 26 is fully powered, the control calculations are performed, and the output is output to the ammonia flow rate control valve 42.

(4) A turbine piston control monument that uses the signal from the main steam pressure transmitter 31 as human power and outputs the result of control calculation to the turbine steam valve 15 to control it.

(5) IPR (initial pressure setting) control in which the signal from the main steam pressure transmitter 31 in front of the load limiter 19 is manually input, and the result of control calculation is output to the load limiter 19.

(6) The signals from the water meter water level transmitter 33 and the deaerator water level transmitter 28 are all powered, and the results of the control calculation are output to the deaerator water level control valve 17 and the condenser water level control valve 16; Condenser/deaerator control controls this.

(Oil temperature control that performs control calculations as all signals from the oil temperature transmitter 34 of the steam turbine 21 and outputs them to the oil temperature cooling temperature control valve 18 to control this.

Note that 27 is a deaerator internal pressure transmitter, and p132 is a main steam temperature transmitter. These are the control device 4D, respectively.
is input to the input device 38 of.

Temperature control of conventional energy savers was carried out by the control system shown in Figure 2.As is clear from Figure 1, this control system consists of an advance value circuit section that receives the gas turbine output and atmospheric temperature as inputs. , and a temperature control unit that receives the drum pressure and the temperature of the water at the outlet of the economizer as input.

And the signal values obtained by these advance value circuit section and temperature control section? The control signal is obtained by adding the total amount and subtracting the total feedback signal of the economizer recirculation flow rate.

First, the preceding value circuit will be explained. By using the atmospheric temperature as an input to the first function generator 43, the gas turbine rated output at that atmospheric temperature is determined. By inputting the gas turbine output into the divider 44 and dividing it by the rated output determined as described above, the gas turbine output expressed as a percentage is determined.

This is input to the third function generator 45 to determine the advance value of the economizer recirculation flow rate as a programmed function of the percentage turbine output. The preceding value of this flow rate (32nd function generator 4
5), and the correction coefficient ft, determined by the fourth function generator 48 to perform the atmospheric temperature correction, are supplied to the multiplier 46 to calculate their product. This determines the final economizer recirculation flow rate advance value.

However, up to the GT (gas turbine output fire), the i"o" signal generator 49 generates the flow value "zero" as the preceding value signal through the analog switches 50 and 47 and the second
It is input to an adder 57.

After the GTffi is turned on, the analog switch 50 switches the input and selects the output of the signal generator 51. The signal generator 51 outputs the flow rate value rz 5 T/HJ t-, and this signal is supplied to the second adder 57 via the analog switch 50.47'e.

Furthermore, after the addition of a GT (gas turbine), the 1'''0# signal generator 4, which generates an output from the 3rd analog switch 50,
9 "zero" flow rate or l'-2 of signal generator 51
Instead of the 5T/HJ flow rate output 1 shift, the program advance value flow rate determined from the gas turbine output and atmospheric temperature mentioned above is selected by the analog switch 47 and added to the adder 57. 2 A brief summary of the timing described above is as follows.

(1) Before GT ignition...Preceding value flow rate is 0 (T/H,
).

(2) After GT ignition and before GT addition...The preceding value flow rate is 2
5 (T/H).

(3) After adding GT...Preliminary value flow rate is determined as program No. 16 for gas turbine output and atmospheric temperature.

In the single-force temperature control system, the drum pressure is controlled by the second function generator 52.
The drum saturation temperature is determined by inputting the first
A subtracter 53 calculates the deviation from the temperature of the water at the outlet of the economizer. Based on this deviation, the proportional integrator 54 and the differentiator 56
By PID (proportional integral and differential calculations are performed, and the respective outputs are all added together in the first addition a55.

The added signal is supplied to the second adder 57 and added to the preceding IIi signal mentioned above. The obtained Japanese official title is
A second subtractor ms is provided where the economizer recirculation feedback signal is subtracted to output the required recirculation flow rate. The foot of the recirculation term is a proportional integrator 59
PI is calculated and used to drive the economizer recirculation condenser recovery (flow rate adjustment) valve 11 to the required position.

Here, the fourth analog switch 60 is a manual valve. When operating, the input of the analog memory 61 is selected and the signal amount is increased or decreased using the increase/decrease button 62.

The above is a conventional control system, and when such control is performed, the exhaust gas temperature of the gas turbine (solid line A) and the GT (gas turbine) output (solid line ) changes.

In FIG. 3A, the horizontal axis represents time (6), the vertical axis represents temperature (6), and output [kW)' (il-1).

Further, in accordance with the change in the GT output, the economizer recirculation flow rate advance value signal changes, as shown by the broken line in (■) in FIG.

In FIG. 3, the horizontal axis represents time [t], and the vertical axis represents flow rate f4/H)t.

Due to the addition of this advance value signal, the economizer recirculation flow rate is
It fluctuates as shown by the solid line I in FIG.

As is clear from Figure 3 (5), the reason why the economizer recirculation flow rate value is not stable is that it changes with respect to the drum saturation temperature as shown by the CJK line and the dashed line in Figure 3. There is a 10 to 15 minute delay in the water supply temperature at the outlet of the economizer, which causes a large deviation, and the drum saturation temperature remains at a constant temperature, while the water supply temperature at the outlet of the economizer also remains at drum saturation. This is because there are parts where the deviation becomes small because the temperature reaches close to that level.

In Figure 3 (Q), the horizontal axis is time (6), and the vertical axis is temperature (6). The time, GT ignition, and GT combination are shown.

The temperature control device of a conventional energy saver as shown in FIG.
The disadvantage of ID calculation is that it is difficult to control both the large temperature deviation portion and the small temperature deviation portion.

That is, for example, if the control constant is adjusted for a portion where the temperature deviation is large, the responsiveness of IIJ groaning will be poor in a portion where the temperature deviation is small.

On the other hand, if all control constants are adjusted to areas where the temperature deviation is small, the economizer recirculation flow rate values corresponding to the areas where the temperature deviation is large will all increase, since even the slightest temperature deviation T will be responded to. become.

In Figure 3, (Q) is an example where the control constant is set at an intermediate point between a small temperature deviation area and a large temperature deviation area. Recognize.

〔the purpose〕

The purpose of the present invention is to eliminate the above-mentioned drawbacks, to completely prevent steaming from occurring in energy savers such as waste heat recovery type combined power generation plants and drum boilers, and to reduce the temperature of the outlet water supply of the energy saver. [Drum Saturation Temperature]--An object of the present invention is to provide a heating control device for a fuel economizer that is capable of suppressing the temperature at which the TC is installed.

〔overview〕

In order to achieve the above object, the present invention subtracts the feedback signal of the economizer recirculation flow rate from the preceding value signal during the plant startup period when the temperature deviation between the drum saturation temperature and the economizer outlet feed water temperature is large. Then, a control signal is obtained to control the recirculation flow, and from the point when the temperature deviation is reduced to a predetermined value, the temperature control device is utilized to add it to the preceding value signal, and from now on, all of the feedback signals are By subtracting the economizer recirculation flow control? It is distinctive in that it is done this way.

〔Example〕

FIG. 4 is a diagram showing the control system of the economizer temperature control device according to one embodiment of the present invention. In the figures, the same reference numerals as in FIG.
The same or equivalent parts are hailed.

The output signal of the first subtracter 53 is input to the monitor relay 63 , and the output of the monitor relay 63 is input to the AND circuit 66 . The AND circuit 66 also receives a signal when 1'-GT is added. The cutting edge of the first adder 55 is manually input to the second analog switch 64. The output of the second ``0'' signal generator 65 and the output signal of the AND circuit 66 are input to the second analog switch 64 .

The circuit operation of this embodiment will be described below.

The drum saturation zero pressure is input to the second function generator 52-,
The drum saturation temperature is determined. In the first subtractor 53, the force i
) Calculate the deviation from the coal machine outlet feed water temperature, perform PID calculation, and when the temperature deviation becomes 3C or less, monitor relay 6
3, p'''1#'b is input manually to the AND circuit 66.

When the GT combined adult condition temperature deviation is 3C or less, the AND circuit 66 generates an output of ``''12, which is input to the second analog switch 64. As a result:
), the output of the r11 adder 55 is selected instead of the zero input of the second signal generator 65. The output of the second analog switch 64 is added to the preceding value signal in the second adder 57 as described above. Thereafter, control of the economizer recirculation condenser recovery (flow rate adjustment) valve 11 is executed in the same manner as in the conventional example shown in FIG.

The above control timing can be briefly summarized as follows.

(1) GTT fire front...The light value flow rate is 0 [T/H].

(2) From after the GT layer fire to just before the GT merger...the advance value flow rate is 25.

(3) After GT combination... Deviation between drum saturation temperature and economizer outlet water supply temperature - When it is 3C or more, the preceding value is output as a program function of gas turbine output and atmospheric temperature concealment. Controlled only by value.

(4) After the GT is added and the temperature deviation becomes 3C or less...The zero output of the second analog switch 64 is switched to the temperature control signal. '1p1 temperature control is started,
Superimposed on advance value control.

By adopting the above control procedure, the exhaust gas temperature and G
The T output changes as shown by the solid line A1 in Figure 5(A), fc,
In this case, the economizer recirculation advance value signal becomes as shown by the broken line in FIG. 5 (2), and the economizer recirculation flow rate becomes as shown by the solid line in FIG.

Temperature control starts when the deviation between the drum saturation temperature and the economizer outlet water supply temperature becomes, for example, an arbitrary set value of 3C or less (T3 in the figure). As clearly shown by the dashed line, it is controlled to be almost constant.

As mentioned above, control is performed using the preceding value until the temperature deviation becomes 3C or less, and from the moment it becomes 3C or less, temperature control is performed. With the starting two-stage control operation, the outlet feed water temperature of the economizer is controlled, and the control effectiveness is significantly improved.

When the present invention is applied to a general boiler, in shell flow type boiler 2, the water supply pressure of the economizer is generally low, so the saturated temperature is higher than the furnace temperature υ, and the stiching in the economizer is Therefore, the present invention is not applicable because there is no need to perform temperature control.

However, the present invention is fully applicable to drum boilers if the following points are taken into consideration.

In a combined cycle power plant, the radiation source corresponding to POI 2 is the exhaust heat of the gas turbine, as explained in the first embodiment, and the recirculation flow rate of the economizer is proportional to the temperature of the exhaust heat. 1st shift ahead? I have a lotus to give.

In contrast, in a typical drum boiler, heat is provided by a burner in a furnace. Therefore, in a boiler, either give the full value of the economizer recirculation flow rate to the furnace temperature, or, since burner fuel is proportional to the furnace temperature, economizer recirculation to the burner fuel flow rate. Either give the preceding value of the flow rate.

FIG. 6 is a diagram illustrating a control system of a temperature control device for an economizer according to another example of the present invention. In the figure, the same reference numerals as in FIG. 4, which shows the control system for the temperature control signal of the economizer of the combined cycle power plant, represent the same or equivalent parts 2.

Comparing the two, in the structure of the advance value control section! A
However, the contents of the control means are almost the same, and the signal of the burner fuel flow rate from the advance value control section is inputted to the first control generator 43, and the advance value of the economizer recirculation flow rate is output.

Furthermore, the drum saturation temperature is calculated from the drum pressure, and from the point when the deviation between the drum saturation temperature and the economizer outlet water supply temperature becomes 3C or less, the temperature control circuit is determined. Take advantage of this by adding the temperature control value to the preceding value. In this way, the present invention can be sufficiently applied to a general drum boiler by changing the structure of the advance value control section.

〔effect〕

As mentioned above, the present invention is designed to control the temperature if control of waste heat, recovery type combined power generation plants, drum-type boilers, etc., using drum saturation temperature and energy saving device 160 feed water temperature. While the difference in m is large, the economizer recirculation flow rate is fully controlled using the preceding value, and when the deviation becomes small to the set value, temperature control a1 is fully started and is carried out superimposed on the preceding value control. This has the advantage that it can respond sufficiently to large temperature changes as well as small temperature changes.

This two-stage temperature control method using switching has good responsiveness to any of the temperature deviations described above, and has a large control effect.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the schematic configuration of an exhaust heat recovery type combined 9-3 basket plant, Figure 2 is a diagram showing the temperature control system of a conventional energy saver, and Figures 3 (A) to (Q are conventional FIG. 5 is a diagram showing the control timing and control response according to the present invention, and FIG. 6 is a diagram showing the control system of the temperature control device of the economizer according to another embodiment of the present invention. ...Gas turbine, 8...Coal economizer, 11...Coal economizer recirculation condenser recovery valve, 24...Coal economizer outlet feed water temperature generator 1g generator, 25...Coal economizer Recirculation flow generator 1g, 4
3... First barrier generator, 47... First analog switch, 49...@1'''0# signal generator, 52...
Second function generator, 53...8g1 subtractor, 54...
Proportional integrator, 55... first adder, 56... enemy divider, 57... second adder, 58... second subtractor, 63
...Monitor relay, 64...Second analog switch, 65...Second ''0# signal generator, 66...AND circuit. 5th CfJ 1b DingHT2
(t)4
m

Claims (1)

[Claims] 1. A means for heating the economizer, a first function generator that generates all the preceding values according to the heating temperature, a first function generator that generates the ``01 output'' (No. N generator), By the heating means,
When the economizer is not heated, the ``'02 output of the 110'' signal generator is selected, and when the economizer is heated, the first analog is selected as the entire output value of the first function generator. a second function generator that calculates the saturation temperature of the drum based on the drum pressure; a means for detecting the outlet water supply temperature of the economizer; a first subtractor for calculating, a means for calculating the target value of the economizer recirculation flow rate based on the recorded temperature deviation, and a second ``0'' signal generator for generating a ``0#''output; While the two conditions of the temperature difference becoming less than a predetermined value and the means for heating the economizer being started are not satisfied, selecting the cutting edge of the second '''02 signal generator; Said 2
a second analog switch that outputs the full target value of the economizer recirculation flow rate when the condition is met; and a second adder that adds the output of the first analog switch and the output of the second analog switch. , a second subtractor for subtracting the output of the economizer recirculation flow rate transmitter from the output of the second adder; and an output of the second subtractor. means for controlling the economizer recirculation flow rate based on t
Equipped with all features: Economizer temperature control device◎