JPS5816109B2 - Liquid level control device for brackish water drum in solar thermal utilization equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid level control device for a brackish water drum in a solar thermal utilization facility, and is capable of reducing the labor of an operator by reliably automatically controlling the liquid level of a brackish water drum, which was conventionally performed manually. This is what we are trying to reduce.

Steam exiting from a brackish water drum in a solar thermal facility is usually supplied to a load such as a power generation turbine or a pressurized water tank.

In addition, the pressure inside the pressure water tank is normally set to be considerably higher than the pressure supplied to the power generation turbine for efficiency reasons.

On the other hand, solar energy fluctuates significantly depending on the weather, so
It is heated and evaporated by solar energy.

The steam pressure in the brackish water drum fluctuates and the state of the gas-liquid mixture below the liquid level in the brackish water drum changes, so when the amount of water supplied is changed to keep the liquid level constant, the liquid level changes. The response of the level, the so-called process characteristics, changes.

Therefore, in order to stabilize the liquid level in the brackish water drum under different pressure conditions, it is necessary to change the gain of the liquid level control system in the brackish water drum according to the pressure change in the brackish water drum so that it is always approximately equal to It is best to ensure optimal control.

The present invention was made in consideration of the above circumstances, and includes a pressure detector that detects the pressure in a brackish water drum that stores steam evaporated by solar energy, and a pressure detector that detects the pressure in a brackish water drum that stores steam evaporated by solar energy. a functional calculator that performs calculations;
a level detector that detects the liquid level of the brackish water drum; a controller that receives a signal from the level detector and calculates an output signal to maintain the liquid level of the brackish water drum at a target value; The multiplier is equipped with a multiplier that receives the output signal of By changing the gain of the control system, the liquid level in the brackish water drum can be stabilized even if the pressure inside the brackish water drum changes over a wide range, and the labor of the operator can be reduced.

An embodiment of the present invention will be described below with reference to the drawings.

In Fig. 1, solar energy 1 concentrated by a reflecting mirror heats an evaporation tube 2 of a heat absorber, and water flowing through the evaporation tube 2 is heated and evaporated, and is stored as steam in a brackish water drum 3. .

The stored steam is supplied from the steam pipe 4 via the steam flow rate control valve 12 to a load such as a power generation turbine or a pressure water tank serving as a heat storage device.

The flow rate adjustment of the steam supplied to this load is performed by the brackish water drum 3.
This is done by controlling the internal pressure to maintain it within a predetermined range.

That is, the pressure in the brackish water drum 3 is detected by the pressure detector 7 installed in the steam pipe 4, and this detection signal is input to the pressure regulator 14, which adjusts the pressure so that it matches a predetermined target value. The operation signal is given as a set value to the steam flow rate controller 13.

Next, the controller 13 sends a signal to the steam flow rate control valve 12 to manipulate the opening degree of the steam flow rate control valve 12 so that this set value and the output value of the detector 11 that detects the steam flow rate supplied to the load become equal. Output to.

As described above, the flow rate of steam supplied to the load is adjusted, but on the other hand, it is necessary to supply water to the brackish water drum 3 in order to keep the liquid level in the brackish water drum 3 constant. .

For this purpose, the level detector 5 detects the liquid level of the brackish water drum 3, and upon receiving this signal, the level controller 6 calculates an operation signal and inputs it to the multiplier 9. An output signal from a function calculator 8 (or a ratio coefficient calculator) connected to the pressure detector 7 is input.

The liquid level adjustment signal of the brackish water drum 3 outputted from the multiplier 9 based on the above two input signals is transmitted to the control valve 10, and the control valve 10 receives the liquid level adjustment signal of the brackish water drum 3 inputted from the multiplier 9. The valve opening degree is controlled accordingly.

That is, the loop gain of the liquid level control system for the brackish water drum 3, which is composed of the level detector 5, the controller 6, the multiplier 9, and the control valve 10, is changed in accordance with the brackish water drum pressure.

Now, as an example, the output characteristics of the function calculator 8 in the case of a 50KW power generation plant are shown in FIG.

In Fig. 2, the horizontal axis shows the pressure inside the brackish water drum detected by the pressure detector 7, and the vertical axis shows the output of the function calculator 8.The output characteristics indicate that the pressure inside the brackish water drum 3 is As the water level increases, the output of the function calculator 8 increases, that is, the gain of the liquid level control system of the brackish water drum 3 increases.

Next, the operation of the apparatus constructed as shown in FIG. 1 will be explained with reference to FIG.

Now, the target value of the pressure inside the brackish water drum 3 is 4.5 kg/c.
Assuming that the operation is performed so that rAG is achieved, the output of the function calculator 8 is 48%, and the output of the controller 6 is corrected by this signal (the loop gain is corrected), and under the optimal control conditions. be driven.

In this state, if some disturbance occurs, for example, if the amount of steam supplied to the load decreases, the level of the two liquids in the brackish water drum 3 tends to increase, and the output of the controller 6 decreases.

Therefore, the output of the multiplier 9 and further the opening degree of the control valve 10 are reduced, the amount of water to be supplied is reduced, and an increase in the liquid level of the brackish water drum 3 is suppressed.

Also, contrary to the above, when the steam flow rate increases and the liquid level in the brackish water drum 3 decreases, the amount of water supplied to the brackish water drum is increased by the same effect as described above, and the liquid level in the brackish water drum 3 decreases. The decline is suppressed.

Due to the above-mentioned actions, the target value 4 of the internal pressure of the brackish water drum 3.
At around 5 kg/crttG, liquid level control of the brackish water drum is performed stably.

Here, the target value of the pressure inside the brackish water drum 3 is 8 kg/crr.
Assume that the transition occurs when the vehicle is operated at tG.

In this case, the output of the function calculator 8 is 63%, and the output of the controller 6 is corrected with this signal.

In other words, the target value is '5! ? 8 kg from /ca'G state
Considering that the process characteristics have changed due to the transition to the /crttG state, the gain of the controller can be increased accordingly, and almost optimal control conditions can be automatically set.

If a disturbance occurs under these conditions, other equipment will be rated at 4.5
The same effect as when operating at the target value of kg/cyyiG is achieved, and stable liquid level control of the brackish water drum 3 can be achieved.

As described above, according to the present invention, the liquid level in the brackish water drum can be stably controlled even when the pressure inside the brackish water drum changes over a wide range, and the labor of the operator can be reduced.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention, FIG. 1 is a diagrammatic system diagram, and FIG. 2 is a diagram showing the relationship between the brackish water drum pressure and the output of the function calculator. 1... Solar energy, 3... Brackish water drum, 7... Pressure detector, 8... Function calculator, 5... Level Detector, 6...controller, 9...multiplier.

Claims (1)

[Claims] 1. A pressure detector that detects the pressure in the brackish water drum that stores steam evaporated by solar energy, a function calculator that performs calculations according to the pressure detected by the pressure detector, and a liquid level of the brackish water drum. A level detector that detects the level, a controller that receives the signal from the level detector and calculates an output signal to maintain the liquid level of the brackish water drum at the target value, and an output signal from the controller. A liquid level control device in a brackish water drum of a solar heat utilization facility, comprising a multiplier that receives an output signal from the above-mentioned functional calculator and generates a liquid level adjustment signal for the brackish water drum.