JPS63812B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a fluid turbidity control device.

By the way, industrial water used in factories requires water quality below a certain predetermined turbidity. For this purpose, the raw water is supplied to the factory after its turbidity is reduced through a turbidity reducing device (filtration device, etc.).

Recently, in order to conserve resources and reduce costs, there has been a trend to mix untreated turbidity water and turbidity-reduced treated water to produce water with a predetermined turbidity and use it as factory water. However, such equipment requires (1) rapid response to changes in raw water turbidity, turbidity after treatment, changes in turbidity settings, and fluctuations in flow rate; (2) low reliability of turbidity meters; This is a problem, and the dead time and time constant are large, making control extremely difficult.

Therefore, it is an object of the present invention to completely solve the above-mentioned problems. In other words, in this invention, the above problem (1) can be solved by performing feedforward control using theoretically calculated values.
(2) is completely resolved by allowing the turbidity control signal to participate in the control within a certain limited range.

This invention will be explained below.

In this invention, a fluid having an original turbidity Di is taken in at an original flow rate Fi and is divided into two parts, a bypass side and a turbidity treatment side, the bypass side remains untreated, and the turbidity treatment side has a turbidity Process turbidity through reduction equipment
Regarding the device which later mixes both as D ₁ and obtains the set turbidity Ds, there is a regulator that compares and calculates the final turbidity D ₀ after mixing with the set value Ds, and a controller that is connected to the output of this regulator. , an upper and lower limiter for giving upper and lower limit values, and an output O of this upper and lower limiter.
a divider for dividing by setting input Y, the difference between the set turbidity Ds and the original turbidity Di or the treated turbidity D1, the difference between the original turbidity Di and the treated turbidity D1, and the an arithmetic unit that calculates the flow rate on the bypass side or the turbidity processing side to make the final turbidity D0 into the set turbidity Ds based on the original flow rate Fi, and multiplies the output of this arithmetic unit and the output of the divider. A multiplier is provided, and the flow rate on the bypass side is controlled using the output of the multiplier {(Ds-D ₁ /Di-D ₁ )×Fi×O/Y} as a set value of the unprocessed bypass flow rate. This is what I did.

Next, an embodiment of the present invention will be described with reference to FIG.

In Figure 1, raw water is introduced through a raw water pipe 1, the raw turbidity Di is detected by a turbidity meter 2 installed midway through the raw water, and it is divided into two parts at the point where it exits the flow meter 3 at the subsequent stage, and is divided into two parts on the bypass side. The raw water passes through a flow meter 6 and a control valve 7. On the other hand, the raw water on the turbidity treatment side passes through the turbidity reduction device 4, and after measuring the treated turbidity _D1 after the turbidity treatment with the turbidity meter 5, it is mixed with the untreated raw water on the bypass side, The final turbidity is measured by the turbidity meter 8 and then sent to the demand end.

In addition, the calculator 9 calculates the value (Ds−D ₁ /Di−D ₁ )×Fi from the raw turbidity Di, the raw flow rate Fi, the treated turbidity D ₁ after turbidity reduction, and the set turbidity Ds. , this is the calculated value of the bypass flow rate to bring the turbidity after mixing to the set turbidity Ds. Therefore, this value is calculated based on the balance of the amount of turbidity components as shown in FIG. In other words, F ₁ = (Ds−D ₁ /Di−D ₁ )×Fi ……(2) is obtained. In this equation (2), (Di-D1) indicates the processing capacity of the turbidity reduction device 4, and the balance of the amount of turbidity components is calculated by taking this processing capacity into account. Then, the output of this arithmetic unit 9 is applied to a multiplier 14.
lead to. On the other hand, the final turbidity _D0 after mixing is detected by the turbidity meter 8, which is guided to the regulator 10, where it is compared with the set value Ds which is the final turbidity, and the adjustment output is sent to the upper and lower limiter 11. Put it in. The upper and lower limit limiter 11 multiplies the upper and lower limit values H/L by centering on Y (%), and the output O is sent to the divider 13
At the same time, divide Y (%) by the value set in the setting device 12 to obtain a division value O/Y. This is led to the multiplier 14 and multiplied by (Ds-D ₁ /Di-D ₁ )×Fi from the arithmetic unit 9 to obtain (Ds-D ₁ /Di-D ₁ )×Fi×O/Y...( 3) Get. This is given as a set value to the bypass flow rate regulator 15, and the bypass flow rate is adjusted via the control valve 7.

In this way, as can be seen from equation (3), even if any of the original turbidity Di, treated turbidity D ₁ , predetermined turbidity set value Ds, and raw flow rate Fi changes, the bypass flow rate set value Ds The calculation is corrected, and the control system quickly responds to disturbances. Further, the correction by the adjustment output of the turbidity controller becomes O/Y in equation (3). Although the above embodiment describes turbidity control of industrial water, etc., the object of turbidity control is not limited to fluids, and can also be applied to, for example, turbidity control of gases containing smoke. Needless to say. For example, Y
= 50% upper limit limiter 11 control value upper limit H = 55
%, and the lower limit L=45%, O=55% to 45%, and O/Y=1.1 to 0.9.

In other words, the correction of the bypass flow rate from the turbidity controller is limited to a range of 1.1 to 0.9, that is, ±10%, so even if the turbidity meter 8 fails, this control device will not go out of control and will remain within a reasonable range. We can provide a safe system that allows you to continue driving within a safe range.

Another example would be to control the flow rate on the turbidity treatment side, that is, (Fi-F ₁ ) in Figure 2, and from equation (2), Fi-F ₁ = Fi × ( Control is performed so that 1-Ds-D ₁ /Di-D ₁ ) = (Di-Ds/Di-D ₁ ×Fi (4) becomes the calculated value of the flow rate on the turbidity treatment side.

Although the above description has been made regarding the configuration using analog instruments, the present invention can also be applied to the case where software processing is performed using a digital controller or the like without changing the gist.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing the balance of turbidity components used to explain the calculation formula. 1... Raw water pipe, 2, 5, 8... Turbidity meter,
3, 6...flow meter, 4...turbidity reduction device, 7...
Control valve, 9... Arithmetic unit, 10... Regulator, 11...
...Upper/lower limiter, 12...Setter, 13...Divider.

Claims (1)

[Claims] 1. A fluid with an original turbidity Di is taken in at an original flow rate Fi and is divided into two, a bypass side and a turbidity treatment side, the bypass side remains untreated, and the turbidity treatment side Then, the treated turbidity is set to D1 through the turbidity reduction device.
In the process of mixing both to obtain the final turbidity D0, the difference between the set turbidity Ds and the original turbidity Di or the treated turbidity D1, and the difference between the original turbidity Di and the treated turbidity D1. a computing unit that calculates a flow rate on a bypass side or a turbidity processing side for changing the final turbidity D0 to the set turbidity Ds based on the difference and the original flow rate Fi; and the final turbidity D0 and the set turbidity. A limiting section limits the output obtained by comparing and calculating Ds to upper and lower limits, and relates this limited output O to a setting input Y corresponding to the process to obtain an output that limits the control operation range; A turbidity control device comprising: a control unit that predictably controls a flow rate on a bypass side or a flow rate on a turbidity treatment side using an output related to the output of the arithmetic unit as a set value. 2 The computing unit calculates the difference between the set turbidity Ds and the raw turbidity Di or the treated turbidity D1, and the raw turbidity Di.
Based on the difference between and the treated turbidity D1 and the original flow rate Fi, calculate the flow rate on the bypass side to make the final turbidity D0 the set turbidity Ds by (Ds − D1 / Di − D1) × Fi The turbidity control device according to claim 1, characterized in that: 3 The computing unit calculates the difference between the set turbidity Ds and the raw turbidity Di or the treated turbidity D1, and the raw turbidity Di.
Based on the difference between and the treated turbidity D1 and the original flow rate Fi, the flow rate on the turbidity processing side to make the final turbidity D0 the set turbidity Ds is (Di-Ds/Di-D1)×Fi The turbidity control device according to claim 1, characterized in that the turbidity control device calculates by: