JPS6040761B2 - Auxiliary steam control system - Google Patents

Description

[Detailed description of the invention]

The present invention relates to auxiliary steam control for a steam power generation plant, and particularly to optimization of auxiliary steam distribution at unit startup. Generally, in a steam power generation plant, steam is generated from its own unit after a certain period of time has passed after the boiler is ignited. However, steam power generation units require auxiliary steam even before ignition. The main sources of auxiliary steam consumption are as follows. {11 For common equipment within the plant (e.g. heating, flue gas desulfurization equipment) ■ Deaerator Removes dissolved gases from the water supplied to the heating skin boiler, so the higher the temperature, the lower the solubility of the gases. Taking advantage of the properties of
After removing dissolved gas, water is supplied to the boiler, and auxiliary steam is used to heat the deaerator. '3} Steam air preheater (amAirHeate for S)
(hereinafter abbreviated as SAH) The air for combustion competition is air heated by an air heater (SAH).
(hereinafter abbreviated as AH), the air is preheated by foothill gas before being sent to the furnace, but an SAH is installed in front of the AH to subheat the air. SAH uses steam for heating and uses auxiliary steam. ■ Fuel heater (amConvere to S)
When heavy oil (hereinafter abbreviated as SO) is used as fuel, the fuel is preheated and sent to the burner, and auxiliary steam is used for SC heating. '5) Turbine casing warming In order to reduce the temperature difference between the steam temperature during turbine air permeation and the casing metal temperature, the casing is warmed, which also uses auxiliary steam. In addition, as a source of auxiliary steam, an in-house boiler or steam from other units already in operation is used. After the self-unit steam is generated, the system switches to self-generated steam. Until now, there was no system that unifiedly controlled the auxiliary steam system. A conventional control method will be explained based on FIG. In FIG. 1, first, the solid line represents the steam line, and the dotted line represents the signal line. The auxiliary steam generation source 1 is connected to the auxiliary steam header 15 via a throttle valve 6a and a check valve 7a. The self-unit steam generation source 2 is also connected to the auxiliary steam header 15 via a throttle valve 6b and a check valve 7b. Auxiliary steam consumption destinations 14a, 14b, 14c, etc. are connected to the tip of the auxiliary steam header turtle 5 via control valves 9a, 9b, throttle valve 9c', etc. The temperature is measured by a temperature sensor 3a, and the pressure is measured by a pressure sensor 4a.The flow rate of steam flowing out from the auxiliary steam generation source is measured by a flow rate sensor 5a.Similarly, the temperature of the own unit steam generation source 2 is measured. is measured by the temperature sensor 3b, the pressure is measured by the pressure sensor 4b, and the flow rate of steam flowing out from the self-unit steam generation source is measured by the flow rate sensor 5b.The flow rate, pressure, The temperature is measured by the flow rate sensor oa, the pressure sensor 11a, and the temperature sensor 12a, and the data is input to the local controller 13a.Similarly, the flow rate, pressure, and temperature of the steam flowing into the auxiliary steam consumption destination 14b are measured by the flow rate sensor, respectively. lob, pressure sensor 11b, and temperature sensor 12b, and other data is input to local controller 13b.The flow rate, pressure, and temperature of steam flowing into auxiliary steam consumption destination 14c are measured by flow rate sensor 10c and pressure sensor 11c, respectively. , is measured by the temperature sensor 12c.The flow rate of steam flowing into the auxiliary steam consumption destination 14a is controlled by the control valve 9a, and the flow rate of steam flowing into the auxiliary steam consumption destination 14b is controlled by the control valve 9b.Control valve ga, The movement of gb is controlled by local controllers 13a, 13b, respectively.Local controllers 13a, 13b are connected to flow rate sensors oa, 10b,
Pressure sensors 11a, 11b, temperature sensors 12a, 12b
The data sent from
By inputting water supply flow rate, condensate temperature, etc. (or, if 14b is SAH, air flow rate, inlet air temperature, outlet air temperature, etc.), predetermined control operations are performed. Furthermore, some auxiliary steam consumption destinations do not have a local controller, and an example thereof is shown in 14c. The control of the auxiliary steam consumption destination 14c is carried out by the operator using the throttle valve 9c' while reading the indicated values of the flow rate sensor 10c and the pressure sensor 11c to the temperature sensor 12c.
This is done by moving it manually. The disadvantage of these local controller controls is that each controller independently controls each corresponding auxiliary steam consumer, and there is no interconnection between the auxiliary steam consumers, the status of the auxiliary steam generation source 1, etc. is not taken into consideration at all. Therefore, it is fine if the amount of steam that can be supplied from the auxiliary steam generation source 1 is sufficiently abundant, but if there is a limit to the amount that can be supplied, then only the status of each auxiliary steam consumer is monitored and controlled. , there is a risk that the auxiliary steam generation source 1 will be overloaded and trip, for example in the case of an in-house boiler.In order to prevent this, at present, pressure sensors 8a, 8b are installed on the auxiliary steam generation source side of the control valves 9a, 9b. is installed to monitor the auxiliary steam pressure, input the data to the local controllers 13a and 13b, and when the auxiliary steam pressure decreases, the control valves ga and g
Although safety measures have been taken to reduce the The reality is that such control is not always good.Accordingly, the purpose of the present invention is to comprehensively control each auxiliary steam consumer separately in order to overcome the drawbacks of the prior art as described above. An object of the present invention is to provide an auxiliary steam control system that includes a control device and uses the control device to optimally distribute auxiliary steam to each consumer while monitoring the auxiliary steam supply margin of an auxiliary steam generation source. The configuration of the second
This will be explained according to the diagram. The auxiliary steam generation source 1 and the self-unit steam generation source 2 communicate auxiliary steam and soda 15 via throttle valves 6a, 6b and check valves 7a, 7b, respectively. The flow rate, pressure, and temperature of steam flowing out from the auxiliary steam generation source are measured by a flow rate sensor 5a, a pressure sensor 4a, and a temperature sensor 3a, respectively, and these data are sent to the input processing device 20 of the control device 30.
One entry is entered. The flow rate, pressure, and temperature of the steam flowing out from the self-unit generated steam line are measured by the flow rate sensor 5b, pressure sensor 4b, and temperature sensor 3b, respectively, and these data are also input to the input processing device 20' of the control device 30. . The throttle valves 6a and 6b are valves that are mainly used to fully close the auxiliary steam generation source 1 and the self-unit steam generation line 2 when disconnecting them from the auxiliary steam header 15. There is no direct relationship. In addition, the check valve 7a
? 7b is the auxiliary steam generation source 1 or the own unit steam generation source 2
This valve is provided for the purpose of preventing backflow of steam when the steam is stopped, and this valve is also not directly related to the auxiliary steam control of the present invention. At the tip of the auxiliary steam header 15 are control valves 9a, g.
Auxiliary steam consumption destinations 14a, 14b, etc. via b, 9c, etc.
14c etc. are suitable for lotus. The flow rate, pressure, and temperature of the steam flowing into each auxiliary steam consumption destination 14a, 14b, and 14c are determined by the flow rate sensor 10a,
10b, 10c, pressure sensor 11a, 11b, 11c
The temperature is measured by the temperature sensors 12a, 12b, 12c, and the data is sent to the input processing device 201 of the control device 30.
This is input. The control device 30 includes an input processing device 20, an arithmetic and control device 21, a storage device 22, and an output device 23. The input processing device 201 includes each sensor 3a, 3b,
4a, 4b'5a, 5b, 10a, lob, 10c, 1
1a, lib, 11c, 12a, 12b, 12c, opening signals of control valves 9a, 9b, 9c, physical quantities specific to each auxiliary steam consumer (for example, if 14a is a deaerator, Internal pressure, water supply flow rate, condensate flow rate, etc., and for example 1
4b force SAH, air flow rate, inlet air temperature,
(outlet air temperature, etc.) is input and input processed. The arithmetic control device 21 is connected to the input processing device 20 and the storage device 22, and after processing the data sent from the input processing device 20 and the storage device 22, sends a signal to the storage device 22 and the output device 23. are doing. The output device 23 outputs a predetermined output signal (target value of the local controllers 13a, 13b or the control valve 9c) to the local controllers 13a, 13b according to the calculation results of the arithmetic and control device 21, or directly outputs a predetermined output signal (target value of the local controllers 13a, 13b or the control valve 9c) to the local controllers 13a, 13b. output as a drive signal to. The local controllers 13a, 13b control the control valves 9a, 13b according to the target value signal received by the control device 30.
Control 9b. The functions of the present invention will be explained according to FIG. First, the auxiliary steam supply amount A that can be supplied from the auxiliary steam generation source 1 is determined in advance and stored in the memory 22 (1
). Next, input the steam flow rate B flowing out from the auxiliary steam generation source 1 (0). Calculate auxiliary steam margin C=A-B (
m). Here, the auxiliary steam generation source 1 and the self-unit steam generation source 2 generally do not operate in parallel. That is, before the second unit steam is generated, auxiliary steam is exclusively supplied from the auxiliary steam generation source 1. Furthermore, after the self-unit steam is established, the auxiliary steam generation source 1 is cut off from the auxiliary steam by completely closing the throttle valve 6a, and the auxiliary steam is exclusively supplied from the self-unit generated steam source 2. The amount of steam generated by the own unit is usually sufficiently abundant and does not require comprehensive control as in the present invention.Therefore, the auxiliary steam margin can be simply expressed as C=A-
B, but if the auxiliary steam generation source 1 and the own unit steam source 2 are operated in parallel, the amount of steam that can be generated and supplied by the own unit is a, and the steam flow rate flowing out from the own unit steam generation source is Letting b be the auxiliary steam margin, C=(A+a)-(B+b). In addition, even after the capacity of the own unit steam generation source is not large enough, the own unit steam generation source is established, and the auxiliary steam generation source 1 is switched to the own unit steam generation source 2, the overall auxiliary steam control according to the present invention is performed. It's necessary, at that timing C=
The auxiliary steam margin may be calculated as a-b. In this way, even if the formula for calculating the auxiliary steam margin differs depending on the timing, it is of course possible to switch between the formulas depending on the timing. Once the auxiliary steam surplus amount C is determined as described above, it is possible to increase the auxiliary steam usage amount as a whole by C (of course, there are cases where C is 0).
, and distributes this to each auxiliary steam consumption destination 14a, 14b, 14c, etc. (N). This distribution calculation can be performed by determining the priority of each auxiliary steam consumer in accordance with the plant operation policy, and making an appropriate judgment based on this, the status of each auxiliary steam consumer, the timing of using auxiliary steam, etc. Next, target values for each auxiliary steam consumption destination are calculated based on the results of the distribution calculation (V). An example of this calculation will be explained assuming that the auxiliary steam consumption destination 14a is a deaerator. In this case, the local controller 3a of the auxiliary steam consumer 14a (deaerator) opens and closes the control valve 9a in an attempt to bring the pressure inside the deaerator to the target value given by the control device 30. Inlet feed water and auxiliary steam enter the deaerator, and the two combine and exit as outlet feed water. Also, the inside of the deaerator is always kept in a saturated state. This will be explained below according to FIG. The flow rate of the inlet feed water of the auxiliary steam consumption destination 14a (deaerator) is gi, the enthalpy is hi, the flow rate of the auxiliary steam flowing into the deaerator is saddle, the enthalpy is ha, and the flow rate of the outlet feed water flowing out from the deaerator is Let go, enthalpy be ho, and enthalpy be ho, then the following formula m and formula (2) hold true. qo=g+ga
......

[1} qoho white ghi juboko ha
......■style. }, from ■, h = gh thirty chicks ha…. Since the condition inside the glue g10 ga deaerator and the condition of the water supply at the deaerator outlet are considered to be the same (that is, in a saturated state), the pressure p inside the deaerator can be found by equation (2). p=f(ho) . . . [4] Since the function f can be determined by the steam formula, it can be determined by storing the steam formula in the storage device 22. Regarding the enthalpies hj and ha, if the temperature and pressure of the feed water at the inlet of the deaerator are ti and pi, and the temperature and pressure of the auxiliary steam flowing into the deaerator are ne and pa, then the equation side, equation It is determined by hi=g(ti, pi) ......(5
}ha=g(ta, pa) ......{6
) The function g is also determined by the steam equation. From equations {4-, {5), '6}, the deaerator internal pressure is determined by the deaerator inlet water supply flow rate, the auxiliary steam flow rate flowing into the deaerator, the deaerator inlet water supply temperature ti, It can be determined from the temperature of the auxiliary steam flowing into the deaerator, the water supply pressure pi at the inlet of the deaerator, and the pressure pa of the auxiliary steam flowing into the deaerator. The above data 9, mackerel, ti, ta, p', and pa may be detected by a flow rate sensor, a temperature sensor, and a pressure sensor and input to the input processing device. If the current state is as described above, and the deaerator allocation of the auxiliary steam surplus amount is C, then the auxiliary steam flow rate flowing into the deaerator will be increased by C compared to the current situation, and it will be several tens of C. , can be made. The deaerator internal pressure ps corresponding to the auxiliary steam flow rate C, can be determined using the equations {41, {51, {61} as described above.
Instead of scales, we can substitute solution +C. ). The target value obtained in this way is output to each consumer (W). In an example in which the above-mentioned 14a is a deaerator, the target pressure inside the deaerator is given to the local controller 3a, and the local controller 13a controls the pressure inside the deaerator to the given target value by controlling the control valve 9a. operate. With this, one loop of control is completed, and it is determined whether the auxiliary steam control will be performed next time or not.
After that, the process returns to step 1 again to continue the control, and if the answer is No, the control ends. In the above description, the local controller is not necessarily required, and the control device 30
Of course, it is also possible for the control device 30 to directly control the control valve 9c in DDC based on the target value determined by. As mentioned above, "According to the auxiliary steam control system of the present invention, while constantly monitoring the auxiliary steam flow rate that can be supplied from the auxiliary steam generation source 1,"
Since comprehensive control can be performed that takes into account mutual relationships and priorities, this has the great effect of allowing optimal auxiliary steam distribution for the steam power generation plant as a whole without overloading the auxiliary steam generation source. It is something. Further, the auxiliary steam flow rate that can be supplied by the auxiliary steam generation source is not constant, and may vary using some state quantity as a parameter. Next, when the auxiliary steam margin is positive and close to 0, if control is performed to increase the auxiliary steam consumption until the end, the auxiliary steam margin becomes negative due to overshoot, and the "auxiliary steam generation source j Since there is a risk of overloading, even if the auxiliary steam margin is positive, if it falls below a certain value, the total auxiliary steam consumption at each auxiliary steam consumption destination should not be increased any further. Or, conversely, the control device 30, which consists of the input processing device layer 20, the arithmetic control device 21, the storage device 22, and the output device 23, can be controlled by an electronic computer. Good too.

[Brief explanation of drawings]

Fig. 1 is a conventional system configuration diagram, Fig. 2 is a system configuration diagram showing an embodiment of the present invention, Fig. 3 is a flowchart showing arithmetic processing of the control device of the present invention, and Fig. 4 is auxiliary steam consumption. FIG. 3 is an explanatory diagram for obtaining the pressure inside the tip. 1: Auxiliary steam generation source, 2: Second unit steam generation source, 3a
, 3b; temperature sensor, 4a, 4b; pressure sensor, 5
a, 5b; flow rate sensor, 6a, 6b; throttle valve, 7a,
7b; Check valve, 8a, 8b; Pressure sensor, 9a, 9b
, 9c; control valve, 9c'; throttle valve, 10a, 10b, 1
0c; Flow rate sensor, 11a, lib, 11c; Pressure sensor, 12a, 12b, 12c; Temperature sensor, 13
a, 13b;. Single controller, 14a, 14b, 14c; Auxiliary steam consumption destination, 15; Auxiliary steam destination, 20; Input processing device, 21; Arithmetic control device, 22: Storage device, 23; Output device, 30: Control device . Figure 1 Figure 4 Figure 2 Trout battle map

Claims (1)

[Claims] 1. A detector that measures the flow rate, pressure, and temperature of auxiliary steam flowing out from the auxiliary steam generation source of a steam power generation plant; a detector that measures the flow rate, pressure, and temperature of auxiliary steam flowing into each auxiliary steam consumption destination; A detector that measures the state quantity of each auxiliary steam consumption destination, an input processing device that inputs and processes the data, and an optimal auxiliary steam that uses the data from this input processing device and the data stored in the storage device. An arithmetic and control device that performs control calculations, a storage device that stores necessary data sent from the input processing device and the arithmetic and control device, and necessary information such as steam formula, and a control signal that outputs control signals according to the calculation results of the arithmetic and control device. Consists of an output device that outputs output, and a control valve that opens and closes according to a control signal from the output device to control the flow rate of auxiliary steam flowing into each auxiliary steam consumption destination, and flowing out from the auxiliary steam generation source. Compare the auxiliary steam flow rate with the pre-stored auxiliary steam supply amount from the auxiliary steam generation source, control the overall auxiliary steam consumption according to the deviation between the two, and control the auxiliary steam usage at each auxiliary steam consumption destination. An auxiliary steam control system that optimally distributes and controls auxiliary steam according to the priority of each auxiliary steam consumer under given conditions.