JPH07122488B2 - Reheater steam temperature control method - Google Patents

Description

The present invention relates to a steam temperature control method for a reheater.

[Prior Art] FIG. 1 shows an example of a coal-fired boiler. High-temperature combustion gas burned by a pulverized coal burner 2 of a furnace 1 is generated in a furnace wall portion 3 of the furnace 1 and an upper part of the inside of the furnace 1. After heating the partition wall 4 and the like, the partition wall 4 and the like are guided to the rear heat transfer section 5. The rear heat transfer section 5 is divided by a partition wall 6 into a reheater side flow path 8 having a reheater 7 and a superheater side flow path 10 having a superheater 9, and each flow path 8 A reheater gas damper 11 for controlling the flow rate of the combustion gas flowing through the flow passages 8 and 10, particularly the reheater side flow passage 8, is provided below the and 10.

Compared to the superheater 9 having a spray device or the like, the reheater 7 for reheating the steam after driving the turbine has almost no means for controlling the steam temperature, and therefore, the reheat is performed. Bowl 7
The amount of gas flowing through the reheater-side flow path 8 is controlled by the reheater gas damper 11 via the damper drive unit 13 so that the temperature detected by the reheater outlet temperature detector 12 for detecting the outlet steam temperature is kept constant. The remaining gas is made to flow to the superheater 9 side.

The conventional opening control of the reheater gas damper 11 is controlled by a program for a load command or the like as shown in FIG. 3, and the reheater gas damper 11 includes a reheater 7 side and a superheater 9
The opening and closing of the side is designed to be the reverse operation.

[Problems to be Solved by the Invention] However, the properties of the raw coal, which serves as a fuel for the coal-fired boiler as described above, differ greatly depending on the place of origin, etc., and even within the same coal type due to the influence of moisture etc. It makes a big difference in the heat collection situation.

Therefore, as described above, in the method in which the opening degree control of the reheater gas damper 11 is simply a program for the load command,
When the type of coal changes to one with different properties, the heat collection status of each part of the boiler changes due to the combustion state in the furnace 1, etc., and the optimum opening of the reheater gas damper 11 also changes. Therefore, there is a problem that reheater steam temperature control with high responsiveness cannot be realized.

The present invention estimates the optimum opening degree of the reheater gas damper according to the coal type from the heat collection state of each part of the boiler such as the heat transfer surface of the furnace part, and corrects the basic opening setting signal by the estimated opening signal. By adjusting the opening of the reheater gas damper, the objective is to realize highly responsive reheater steam temperature control.

[Means for Solving the Problem] The present invention provides a method for controlling the reheater steam temperature by adjusting the opening of a reheater gas damper by a basic opening setting signal and a feedback control signal based on a load command. The temperature and pressure of the inlet and outlet of the furnace wall portion, the temperature and pressure of the inlet and outlet of the dividing wall at least detected and input to the furnace heat collection heat calculation circuit to detect the heat collection of the specific furnace portion, The optimum opening of the reheater gas damper corresponding to the furnace heat collection signal is estimated by introducing the furnace heat collection signal to the opening calculation circuit, and the basic opening setting signal is corrected by the estimated opening signal. A method for controlling the steam temperature of the reheater, characterized in that the steam temperature of the reheater is controlled by adjusting the opening of the reheater gas damper by the modified corrected opening signal and the feedback control signal. Is.

[Operation] When the heat collection of each part of the boiler, especially the furnace part, changes due to the combustion state in the furnace, the optimal opening of the reheater gas damper is estimated accordingly, and the estimated opening signal is used to set the basic opening setting signal. Is corrected, the opening degree of the reheater gas damper is corrected according to the change in raw coal properties.

[Examples] Examples of the present invention will be described below with reference to the drawings.

Detectors 14 and 15 for detecting the temperature and pressure of the inlet (upstream side) and the outlet (downstream side) of the furnace wall portion 3 of the furnace 1 in the boiler of FIG. The detectors 16 and 17 for detecting temperature and pressure are provided so that the detectors 14, 15 and 1
The heat collection status of the furnace part 1 can be grasped from the detected temperature and pressure of 6,17. At this time, when the heat collection of the other suspended heat transfer surface 18 and the like is also considered as the part of the furnace 1, the temperature and pressure of its inlet and outlet are also detected. In the figure, 12 is a reheater outlet temperature detection unit that detects the steam temperature at the reheater 7 outlet, and 13 is a damper drive unit.

In FIG. 2, the load command 19 is function-converted by the function generator 20 to obtain the basic opening setting signal 21 of the reheater gas damper,
The basic drive setting signal 21 is used to control the damper drive unit 13, and the temperature detector 12 subtracts the detected steam temperature signal at the outlet of the reheater 7 and the set temperature signal 22 from the steam temperature setter. The difference signal 24 is subtracted by the calculator 23, the difference signal 24 is guided to the PI controller 25, the feedback control signal 33 is guided to the adder 26, which is added to the basic opening setting signal 21 to adjust the damper drive unit 13. I am trying.

Although the control circuit has been conventionally implemented,
In this method, if the optimum opening of the reheater gas damper changes due to a change in furnace heat collection due to a change in coal type, all deviations from the basic opening setting signal 21 are covered by adjustment by the PI controller 25. Therefore, there is a problem in terms of responsiveness.

Therefore, the temperature and pressure detected by the detectors 14, 15, 16 and 17 from the detector 35 of each part of the boiler are calculated by the furnace heat collection heat calculation circuit.
It inputs to 27 to calculate the furnace part heat collection of the furnace wall part 3 and the dividing wall 4 etc., and guides the furnace part heat collection signal 28 to the opening calculation circuit 29 to estimate the optimum opening of the reheater gas damper. The estimated opening degree signal 30 is led to the correction calculation circuit 32 via the function generator 31, and the basic opening degree setting signal 21 is corrected based on the load command 19. Reference numeral 34 represents a corrected opening signal.

In the above, a detector that detects the temperature and pressure at the inlet and outlet of the furnace wall 3 and the temperature and pressure at the inlet and outlet of the dividing wall 4 when the properties of the raw coal change due to changes in the fuel coal type and the like. The signals of 14, 15, 16 and 17 change, and the signals are guided to the furnace part heat collection calculation circuit 27 to calculate the furnace part heat collection, so it is understood as a change in the furnace part heat collection signal 28. .

The opening degree calculation circuit 29 estimates the optimum reheater gas damper opening degree according to the furnace part heat collection signal 28 and outputs the signal 30, so that when the furnace part heat collection signal 28 changes, Accordingly, the estimated opening degree signal 30 also changes, and the correction amount for correcting the basic opening degree setting signal 21 in the correction calculation circuit 32 changes.

Therefore, the basic opening setting signal 21 based on the load command 19 is modified by the raw coal property, and the modified modified opening signal 34
The feedback control signal 33 and the feedback control signal 33 are added by the adder 26 to operate the damper drive unit 13 to adjust the opening degree of the reheater gas damper, which reduces the control by the PI controller 25. Therefore, highly responsive reheater steam temperature control is realized.

In the above embodiment, the case of detecting the heat collection of the furnace part where the influence of the change of the combustion state in the furnace due to the change of the property of the raw coal is most likely has been described, but the heat collection of the parts other than the furnace part is also detected and considered. You may do it.

The steam temperature control method for the reheater according to the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the scope of the present invention.

[Effects of the Invention] As described above, according to the steam temperature control method for a reheater of the present invention, the inlet and outlet of the boiler furnace wall portion, which appear as the fastest change in heat absorption when the property of coal changes. Temperature and pressure of the partition wall, and the temperature and pressure of the inlet and outlet of the dividing wall, and the detected values are input to the furnace heat collection calculation circuit to detect the heat collection of the boiler furnace part, and the boiler furnace Since the optimum opening of the reheater gas damper is estimated according to the heat collection of the part, and the opening of the reheater gas damper is adjusted by correcting the basic opening setting signal with the estimated opening signal. An optimum opening of the reheater gas damper can be obtained according to changes in the properties of the raw coal, and thus an excellent effect that the steam temperature of the reheater can be controlled with high responsiveness can be obtained.

[Brief description of drawings]

FIG. 1 is a front view showing an example of a boiler for carrying out the method of the present invention, FIG. 2 is a control block diagram of the present invention, and FIG. 3 is a diagram showing a conventional reheater gas damper opening control method. is there. 1 is a furnace, 2 is a pulverized coal burner, 3 is a furnace wall part, 4 is a dividing wall, 5 is a rear heat transfer part, 7 is a reheater, 8 is a reheater side passage,
9 is a superheater, 10 is a superheater side flow path, 11 is a reheater gas damper, 12 is a reheater outlet temperature detector, 13 is a damper drive unit, 14
Is a furnace wall inlet temperature and pressure detector, 15 is a furnace wall outlet temperature and pressure detector, 16 is a dividing wall inlet temperature and pressure detector, 17 is a dividing wall outlet temperature and pressure detector, 19 is a load command, 21 is a basic opening setting signal,
27 is a furnace part heat collection calculation circuit, 28 is a furnace part heat collection signal, 29 is an opening calculation circuit, 30 is an estimated opening signal, 32 is a correction calculation circuit, 33
Is a feedback control signal, 34 is a corrected opening signal, and 35 is a detector of each part of the boiler.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinya Nakayama 3-2-16 Toyosu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries Ltd. Toyosu General Office (72) Inventor Shinya Oishi 3-2, Toyosu, Koto-ku, Tokyo No. 16 Ishikawajima Harima Heavy Industries Co., Ltd. Toyosu General Office (56) Reference JP 61-99001 (JP, A) JP 55-160201 (JP, A) JP 58-200907 (JP, A)

Claims (1)

[Claims] 1. A method for controlling the reheater steam temperature by adjusting the opening of a reheater gas damper according to a basic opening setting signal and a feedback control signal based on a load command, the inlet and outlet of a boiler furnace wall. Temperature and pressure of the dividing wall and the temperature and pressure of the inlet and outlet of the dividing wall are input to the furnace part heat collection calculation circuit to detect the heat collection of the furnace part and open the furnace part heat collection signal. To estimate the optimum opening of the reheater gas damper according to the furnace heat collection signal by correcting the basic opening setting signal by the estimated opening signal, A steam temperature control method for a reheater, comprising: controlling a steam temperature of a reheater by adjusting an opening of a reheater gas damper with a feedback control signal.