JPH0380527B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an abnormality detection device that distinguishes various abnormalities in a membrane separation device for each factor and calculates the degree of the abnormality. Conventionally, in a membrane separation device, the required flow rate of a diluted or concentrated solution was monitored, and abnormalities in the device were determined based on changes in this value over time. However, it is impossible to distinguish between each factor from the decrease in flow rate, and since the flow rate of dilute or concentrated solution is a function of the pressure, flow rate, concentration, and temperature supplied to the membrane, comparisons under different operating conditions are difficult. It was extremely difficult. It is an object of the present invention to eliminate this drawback regarding abnormality detection in membrane separation devices, and to provide an abnormality detection device that distinguishes various abnormalities for each factor and calculates the degree of the abnormality. The present invention calculates the theoretical pressure (or the flow rate corresponding to the theoretical pressure) on the inlet side and outlet side (concentration side) before and after the membrane calculated using the performance curve of the pump, the relationship between solute concentration and osmotic pressure, and the flow rate characteristics of the pressure holding means. ) value P ₀ ,
By comparing P ₂ and the readings P′ ₀ and P′ ₂ of these pressure meters, we can determine the pressure condition in the right column from the pressure condition on the membrane inlet side in the left column and the pressure condition on the membrane outlet side in the middle column in the following table. It detects an abnormality by making a judgment as follows, and calculates the degree of abnormality. Membrane inlet side Membrane outlet side Judgment P ₀ <P′ ₀ P ₂ <P′ ₂ Deterioration of membrane performance P ₀ <P′ ₀ P ₂ >P′ ₂ Blockage of flow path P ₀ >P′ ₀ P ₂ >P′ ₂ Deterioration of Pump Performance Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a flow sheet including a control block diagram. Seawater taken by a seawater intake pump (not shown) is sucked into a centrifugal pump (hereinafter simply referred to as pump) 1 through a pretreatment process. Seawater pumped up and discharged by the pump 1 has a pressure P ₀ , a flow rate Q ₀ and a concentration C ₀ detected by the pressure detector 2, and a temperature T ₀ detected by the temperature detector 3. Seawater in this state applies reverse osmosis pressure that is higher than osmotic pressure to the semipermeable membrane 4, resulting in pressure P ₁ ,
Flow rate Q ₁ measured by flow meter 5, fresh water of concentration C ₁ is output, and pressure detected by pressure detector 6
Concentrated seawater with a flow rate of P ₂ , a flow rate of Q ₂ , and a concentration of C ₂ is supplied to the Pelton turbine 7 to recover energy and assist the motor 8 . The control device 9 includes a flow control valve 10 whose output end includes a valve drive device 10' and a turbine inlet nozzle 7' whose stroke is adjusted by the valve drive device 10'.
is connected to the control input terminal of the The contents of the control device 9 will be described. The flow rate Q ₁ on the dilute side of the semipermeable membrane is Q ₁ = A _M K△P ……(1) However, the area of the A _M semipermeable membrane △P≒P _M −π _M ……(2) K Type of membrane and Coefficient determined by temperature P _M Supply seawater pressure near the semipermeable membrane π _M This is the osmotic pressure of the supply seawater near the semipermeable membrane. The control device 9 performs the following calculations. (1) Diluent flow rate Q ₁ is input for setting. (2) A discharge pressure P ₀ of pump 1 is assumed. Since this assumed discharge pressure P ₀ is a calculated value, it may be set constant in advance when the device is started. Further, during operation of the device, the pump discharge pressure P ₀ before the setting change of the lean side flow rate Q ₁ may be used as an assumed value. Block 11 of the control device 9 shows the water head on the vertical axis and the flow rate on the horizontal axis. In the figure, curve 21
shows the performance curve (Q-H curve) of pump 1,
Curve 22 shows the input characteristic curve to the water wheel 7 at the turbine inlet nozzle 7', and curve 23 shows the dilute liquid flow rate Q ₁ of the semipermeable membrane 4. Assuming pump discharge pressure P ₀ , pump discharge amount Q ₀ can be found. (3) Concentrate flow rate Q ₂ = Q ₀ - _{Q 1} , so it can be found by subtracting the set value Q ₁ from Q 0 obtained in item (2). (4) Block 12 shows the osmotic pressure π on the vertical axis and the concentration C _M of the solution on the horizontal axis. Curve 24 shows the relationship between solute concentration and osmotic pressure. The liquid concentration C _M on the supply side of the semipermeable membrane 4 is approximately determined by C _M ≈(C ₀ +C ₂ )/2. The concentrations C ₀ and C ₂ may be determined by the above approximate formula unless the recovery rate Q ₁ /Q ₀ changes significantly. From this relationship, the osmotic pressure π _M can be found. (5) When the temperature of the supplied seawater changes _{significantly} , a temperature detector ₃ is installed to detect the temperature of the _supplied liquid in the supply _piping. The coefficient K is calculated from the diffusion coefficient T of water in the membrane and the temperature D _W /T of the supplied liquid. If the temperature change of the supplied liquid is small, it may be set as a constant. The relationship between T and D _W /T is shown in block 13 by curve 28. (6) The vertical axes of blocks 11 and 12 are shown on the same scale, and the membrane surface pressure P _M on the supply side of the semipermeable membrane 4 is calculated from the discharge pressure P ₀ of the pump 1 assumed in item (2) to the semipermeable membrane 4. It is calculated by reducing the pressure loss P _L1 due to the fluid pipeline of the supply side piping up to. The dilute solution pressure P ₁ of the semipermeable membrane 4 is almost constant, and the dilute solution concentration can be considered to be constant, so the osmotic pressure π ₁ of the dilute solution can be assumed to be constant. Therefore, reverse osmotic pressure ΔP=(P _M −P ₁ )−(π _M −π ₁ ) (3) is calculated. This relationship is illustrated between blocks 11 and 12. (7) Block 15 has the same vertical axis scale as blocks 11 and 12, and the vertical axis shows the pressure ΔP exceeding the osmotic pressure π, and the horizontal axis shows the dilute solution flow rate _Q1 . The line 25 represents Q ₁ =A _M K△P (1), and the dilute liquid flow rate Q ₁ that changes due to the pressure △P exceeding the osmotic pressure is shown in linear proportion. formula
Let Q ₁ calculated by (1) be Q _1CALC . (8) Compare Q ₁ and Q _1CALC set in item (1). If this error is large, return to item (2), reassume pump discharge pressure P ₀ , and repeat items (2) to (8) above in a loop until the error between Q ₁ and Q _1CALC becomes small. Repeat. Here, as shown in block 11, the discharge pressure of pump 1 corresponding to the maximum dilute liquid flow rate Q _1nax is P ₀₁
If the pressure P ₀ assumed in item (2) before becomes Q _1CALC −Q ₁ > 0 in a small range, make the re-assumed P ₀ smaller than the initially assumed P ₀ and Q _1CALC −Q ₁
When <0, the re-assumed P ₀ is made larger than the initially assumed P ₀ . First, the discharge pressure of pump 1 assumed in item (2)
Q _1CALC −Q ₁ > ₀ in the range where P 0 is greater than the discharge pressure P ₀₁ of pump 1 corresponding to the dilute liquid flow rate Q _1nax
When _Q1CALC - _Q1 <0, _the re-assumed _P0 is made smaller than _the initially assumed _P0 . (9) If the calculation error, which is the difference between the set diluted liquid flow rate Q ₁ and the Q _{1 CALC} calculated in items (2) to (8), is within the allowable value, set the concentrated liquid pressure P ₂ to P ₂ = P ₀
−P _L1 −P _L2 . However, P _L2 is the pressure loss due to resistance in the flow path from the semipermeable membrane 4 to the nozzle 7' of the Pelton turbine 7. This means that the characteristic curve 26 of the nozzle 7', on the same scale as block 11 of the control device 9, shows the concentrate pressure P ₂ on the vertical axis and the jet velocity V from the nozzle 7' on the horizontal axis. is shown. The characteristic curve 26 is V=α√2 ₂ where α is a constant and g is the acceleration of gravity.
Block 16 determines V. In the above control device 9, when the dilute solution flow rate Q ₁ is set, the performance curve of the pump 1 is determined, and the relationship between concentration and osmotic pressure is also determined depending on the type of solution, so the discharge pressure P ₀ of the pump 1 and dilution liquid flow rate
The relationship in Q ₁ is uniquely determined. Therefore, the procedures of items (2) to (8) described above can be omitted by compiling them as a numerical table. Also, at the same dilute solution flow rate _Q1 , block 1
As shown in 6, the discharge pressure of two types of pump 1
P ₀ is determined, but the allowable recovery rate is determined by the properties of the semipermeable membrane 4.
Q ₁ /Q should be less than or equal to _0. Choose the one with the smaller required power as the judgment condition. (10) Block 17 shows a valve opening-valve stroke characteristic curve 27, with the horizontal axis representing the valve opening A _V of the nozzle 7' and the vertical axis representing the stroke S of the flow rate control valve 10. When V is determined by block 16, the valve opening of the flow rate control valve 10 is A _V =Q ₂ /V.
is required. Once the valve opening A _V is determined, the stroke S of the flow rate control valve 10 is determined. Since this stroke S is output as a signal from the control device 9, it is amplified by the driver 18 to operate the flow rate control valve 10. As described above, the flow rate control valve 10 is adjusted to obtain the required diluted liquid flow rate _Q1 . In the embodiment, a nozzle whose opening degree can be adjusted at the downstream end of the pump discharge side and a Pelton water wheel operated by the liquid ejected from the nozzle are used as a system pressure holding means, but the present invention is not limited to this, and a simple flow control valve is used. Alternatively, other energy recovery means such as a flow control valve and a reversing pump may be provided. In the device of the present invention, the flow rate Q ₁ of fresh water output from the semipermeable membrane 4 is determined as described above. Now, in the second case, the performance of the semipermeable membrane 4 deteriorates under such operating conditions.
This will be explained using the flow sheet shown in the figure. (1) As already mentioned, the desalination capacity of semipermeable membranes is
Q ₁ = A _M K△P, K = K ₀・(D _W /T)
When the performance of the semipermeable membrane decreases, the coefficient K ₀
becomes smaller, and the flow rate obtained with the same pressure difference △P
Q ₁ decreases. Therefore, in block 15, the slope of the line 25, which is shown as a solid line, increases as shown in a dotted line. If the temperature of the feed liquid is constant, the dilute liquid flow rate Q ₁ decreases and the concentrated liquid flow rate Q ₂ increases. Dilute liquid flow rate Q′ ₁ after change, concentrate liquid flow rate
If Q′ ₂ , then Q ₁ >Q′ ₁ and Q ₂ <Q′ ₂ . (2) Since the opening degree A _V of the nozzle 7' is constant, an increase in the concentrate flow rate Q ₂ causes an increase in the ejection velocity V of the nozzle 7', and as shown in block 16, the concentrate pressure P ₂ becomes P' _2. To increase. That is, P ₂ <P′ ₂ and V<V′. (3) Since the fluctuation in pressure loss P _L = P _L1 + P _L2 in the piping system is small compared to the increase in concentrate pressure P ₂ , pump 1
Since the discharge pressure P ₀ =P _L +P ₂ becomes higher, the discharge pressure P' ₀ of the pump 1 after fluctuation becomes P ₀ <P' ₀ . Therefore, as shown in block 11, the discharge pressure P ₀ of the pump 1 becomes P′ ₀ and the concentration Q−H
This is indicated by the curve 22 shifting to the dotted line side. (4) Therefore, it is determined that the performance of the half-permeable membrane 4 is degraded when P ₂ <P' ₂ and P ₀ <P' ₀ . Therefore, by detecting the pressure before and after the change using the pressure detectors 2 and 6, it is possible to know that the membrane performance has deteriorated. Then, by calculating the coefficient K′ ₀ determined by the new film type, the degree of performance deterioration can be determined. Next, we will discuss the calculation of K′ ₀ . Block 1 from the detected value P' ₂ of pressure detector 6
The flow velocity V' at the inlet nozzle 7' after the change is determined by V'=α√2' or the curve 26 of 6. Since the opening degree A _V is constant, the concentrated liquid flow rate Q' ₂ after the change is determined by Q' ₂ = A _V V'. Using the pump performance curve 21 of block 11, calculate the discharge amount from the changed discharge pressure P′ ₀ of pump 1.
Find Q′ ₀ . The diluent flow rate is Q′ ₁ =Q′ ₀ −Q′ ₂ . The pressure loss P′ _L1 in the pipeline can be calculated as a function of the flow rate, but it is 1/1 compared to the discharge pressure of pump 1.
Since it is a value of about 50 and the fluctuation is within that range, it may be a constant in this case. The supply side membrane pressure P′ _M of the semipermeable membrane changes to P′ _M = P′ ₀ − P′ _L1 . The concentration C′ ₂ of the concentrated solution is determined by C′ ₂ =C ₀ ×Q′ ₀ /Q′ ₂ . Therefore, the average solution concentration C' _M on the semipermeable membrane supply side can be approximately found as C' _M = (C ₀ + C' ₂ )/2. Since the concentration _C'M is known, the osmotic pressure _π'M after change is determined from the curve 24 of block 12. The reverse osmotic pressure △P' is expressed by the formula △P'=(P' _M - P ₁ ) - (π' _M - π ₁ ) However, the dilute solution pressure and its osmotic pressures P ₁ and π ₁ are calculated using constants. K' = Q' ₁ /A _M △P' calculates the coefficient K' that represents the permeation ability of the semipermeable membrane, so by comparing K and K', the degree to which K' is smaller determines the deterioration of the semipermeable membrane 4. The lower degree becomes clear. When the temperature change is large, calculate (D _W /T) from the temperature T detected by temperature detector 3 and find K' ₀ =
Find K/(D _W /T) and compare K ₀ and K' ₀ . FIG. 3 is a control block diagram showing the film deterioration degree detection device. a function generator 11a whose output end has a pump performance curve;
A membrane inlet pressure detector 2 whose output end is connected to the input end of the membrane surface pressure calculator 29, a membrane outlet pressure detector 6 whose output end is connected to the input end of the concentrate flow rate calculator 6b, and one input end of which is connected to the input end of the membrane surface pressure calculator 29. A dilute liquid flow rate calculator 30 is connected to the output end of the function generator 11a, and one input end is connected to the output end of the concentrate flow rate calculator 6b, and one input end is connected to the concentrate flow rate calculator 6b. and the other input terminal is connected to the output terminal of the pump performance curve function generator 1.
1a, and the output end is connected to the input end of the osmotic pressure function generator 12a, and the input end thereof is connected to the dilute solution flow rate calculator 3.
0, membrane surface pressure calculator 29, osmotic pressure function generator 1
2a, the membrane performance deterioration degree calculator 31 whose output end is connected to the membrane performance deterioration degree indicator 32 and the input end of the membrane performance deterioration degree storage section 33; A timer 34 that controls the output time from the performance deterioration degree storage section 33 to the temporal change indicator 35 at intervals, a performance deterioration degree storage section 33, a temporal change indicator 35, and a function generator 11a that represents the pump performance curve described above. , osmotic pressure function generator 12
A, a membrane performance deterioration detecting device is connected to the concentrate flow rate calculator 6b and the like. In the control block diagrams shown in Fig. 3 and after Fig. 3, physical quantities such as input/output pressure, flow rate, concentration, coefficient, etc. are input as voltages and output as voltages, or are digitally controlled. only physical quantity names are shown without using electrical or digital signal names. Concentrate pressure P′ ₂ detected by membrane outlet pressure detector 6
When inputted, the concentrate flow rate calculator 6b calculates Q' ₂ =A _V α√ according to blocks 17, 16, and 11 in FIG.
2gP′ ₂ is calculated and a signal of Q′ ₂ is output. Pump discharge pressure P′ ₀ from pressure detector 2 at membrane inlet
When input, the pump performance curve function generator 11
A is calculated based on block 11 in FIG. 2 and outputs the pump discharge amount _Q'0 . The diluted liquid flow rate calculator 30 serves as an adder and receives inputs Q' ₀ and Q' ₂ and outputs Q' ₁ =Q' ₀ -Q' ₂ . The membrane surface concentration calculator 6c is the pump performance function generator 1.
By inputting the pump discharge amount Q' ₀ of the output signal 1a and the concentrate flow rate Q' ₂ of the output signal from the concentrate flow rate calculator 6b, C' ₂ = C ₀ ×Q' ₀ /Q' ₂ to C' _M = (C ₀ +
C′ ₂ )/2 and outputs the membrane surface concentration C′ _M. In response to this, the osmotic pressure function generator 12a calculates π′ _M = f(C′ The osmotic pressure π' _M is generated from _M ) and outputted to the membrane performance deterioration degree calculator 31. The membrane surface pressure calculator 29 is the pump performance function generator 1
In response to the input Q′ ₀ from 1a, P′ _L1 = a ₁ (Q′ ₀ /Q _R ) where a ₁ is the coefficient of resistance of the pipe from the discharge port of pump 1 to the semipermeable membrane 4 at the flow rate Q _R Then, upon receiving the signal P′ ₀ from the membrane surface pressure detector 2, P′ _M =P′ ₀ −
P′ _L1 is calculated and the membrane surface pressure P′ _M is output. The performance degradation calculator 31 calculates △P' = (P' _M - P' ₁ ) - (π' _M - π ₁ ) from the input membrane surface pressure P' _M and osmotic pressure π' _M , and uses the result and From the input diluent flow rate Q′ ₁
Calculate K' = Q' ₁ / A _M △P', and if the input change from temperature detector 3 is large, calculate K' ₀ = K' / (D _W /T), and determine whether K' ₀ or performance has deteriorated. Calculate and output the degree K′ ₀ /K ₀ . The performance deterioration degree display 32 inputs and displays the coefficient K' ₀ or deterioration degree K' ₀ /K ₀ representing the permeability of the membrane, and the performance deterioration degree storage section 33 sequentially displays the coefficient K at intervals by the timer 34. ₀ or degree of decrease K′ ₀ /K ₀
, and extracts and outputs the past K ₀ or K′ ₀ /K ₀ stored under the control of the timer 34,
The change over time is displayed on the display 35. As described above, when the output of the membrane separation device changes, the degree of decline in membrane performance becomes clear. Next, we will discuss the deterioration in performance of the device due to blockage of the flow path. FIG. 4 is a flow sheet showing the contents of a control device that determines the degree of deterioration in performance of the device due to the flow path. When a flow path in the system is blocked, the discharge pressure P ₀ of the pump 1 increases and the discharge amount Q ₀ decreases. The discharge pressure of pump 1 after the flow path is blocked is P′ ₀ , and the discharge amount is
When Q′ ₀ , pump performance curve 21 of block 11
Therefore, P ₀ <P′ ₀ and Q ₀ >Q′ ₀ . The flow rate Q ₁ of the diluted liquid decreases as the pump discharge amount Q ₀ decreases so that the membrane surface concentration of the feed liquid near the semipermeable membrane C _M = C ₀ /2・
(2Q ₀ −Q ₁ )/(Q ₀ −Q ₁ ), so _CM increases.
It becomes C′ _M. Therefore, along the curve 24 of block 12, the osmotic pressure π _M increases, the reverse osmotic pressure ΔP decreases,
As shown in block 15, a line 25 showing the relationship between the dilute solution flow rate _Q1 and the reverse osmosis pressure ΔP shifts to the dotted line side, and the dilute solution flow rate _Q1 decreases to _Q'1 . On the other hand, pump discharge pressure
An increase in P ₀ generally increases the diluent flow rate Q ₁ .
Therefore, although it differs depending on where the flow path in the semipermeable membrane 4 is clogged, the above two factors that fluctuate the flow rate Q ₁ cancel each other out, and the flow rate Q ₁ either decreases slightly or increases slightly, and the fluctuation range is small. . That is, Q ₁ Q′ ₁
Since Q′ ₂ =Q′ ₀ −Q′ ₁ , Q ₂ >Q′ ₂ and the concentrate flow rate Q ₂ decreases significantly. Therefore, since the nozzle opening degree A _V is constant and the flow rate is Q' ₂ , as shown in block 16, the concentrate flow rate V' and the pressure P' ₂ become P ₂ >P' ₂ , V
>V′. Therefore, when P ₀ <P′ ₀ and P ₂ >P′ ₂ , it is determined that the flow path is blocked. The pressure loss P′ _L1 in the pipe after the flow path is blocked is P′ _L1 = a′ ₁ (Q′ ₀ /Q _R ) ^2However , the resistance coefficient a′ ₁ is the pressure loss when the flow path is blocked at the flow rate Q _R It is. By calculating a′ ₁ from this equation and comparing it with a ₁ (described above), the degree of blockage of the flow path can be determined. Next, we will explain how to find the resistance coefficient a′ ₁ . First, find V′ from P′ ₂ as described above, and since A _V is constant, Q′ ₂ is found. Using the pump performance curve 21 of block 11, find Q' ₀ from P' ₀ and get Q' ₁ = Q' ₀ -
The dilute liquid flow rate Q′ ₁ is obtained from Q′ ₂ . Reverse osmotic pressure is determined by ΔP′=Q′ ₁ /A _M ·K.
Next, as already mentioned, the concentrate concentration C' 2 after the channel is blocked is determined by C' ₂ = C ₀ ×Q ₀ /Q' ₂ , and the membrane surface concentration C _{' M =}
Calculate (C ₀ +C′ ₂ )/2. From block 12, the osmotic pressure π' _M after the channel is blocked is determined. From this, find the membrane surface pressure P′ _M =△P′+(π′ _M −π ₁ )+P ₁ . and
Find P′ _L1 = P′ ₀ −P′ _M , and find a′ ₁ by a′ ₁ = P′ _L1 /(Q′ ₀ /Q _R ). FIG. 5 is a control block diagram showing the flow path blockage degree detection device. Membrane inlet pressure detector 2, membrane output pressure detector 6, pump performance curve function generator 11a, concentrated liquid flow rate calculator 6b, diluted liquid flow rate calculator 30, membrane surface concentration calculator 6c, osmotic pressure function generator The related structure of 12a is the same as the control block diagram of the membrane performance deterioration detection device shown in FIG. The occlusion degree calculator 37 has input terminals as a membrane inlet pressure detector 2 and a pump performance curve function generator 1.
1a, the diluted liquid flow rate calculator 30 is connected to the output end of the concentration and osmotic pressure function generator 12a. The input end of the occlusion degree indicator 38 is connected to the output end of the occlusion degree calculator 37, and the input end of the occlusion degree storage unit 39 is connected to the output end of the occlusion degree calculator 37, and the output end is controlled by the timer 41. The output changes over time indicator 42
It is designed to be added to the input end of . The discharge pressure P' ₀ , discharge amount Q', dilute solution flow rate Q' ₁ , and osmotic pressure π' _M input to the occlusion degree calculator 37 are the same as those explained in FIG. 3. Occlusion degree calculator 37
calculates the reverse osmotic pressure △P'=Q' ₁ /A _M・K from the input diluted liquid flow rate Q' ₁ , inputs the osmotic pressure π' _M from the concentration and osmotic pressure function generator 12a, and calculates the semipermeable membrane. 4. Find the membrane surface pressure P' _M of the supplied liquid in the vicinity from P' _M = △P' + (π' _M - π ₁ ) + P ₁ , and detect the pressure loss P' _L1 in the flow path after the change at the purchase port pressure. Input the discharge pressure P' ₀ from the device 2 and find it by P' _L1 = P' ₀ - P' _M. Then, a' ₁ =P' _L1 /(Q' ₀ /Q _R ) ² is determined using the input Q' ₀ from the pump performance curve function generator 11a. Therefore, the difference or ratio of the coefficients before and after the change, such as a ₁ −a′ ₁ or a′ ₁ /a ₁ , is calculated by the occlusion degree calculator 37.
The flow path occlusion state can be known by outputting the data from the timer and displaying it on the occlusion degree indicator 38, while storing it in the occlusion degree storage unit 39 at regular intervals using a timer and outputting it to the time change indicator 42. . Next, let's talk about the drop in pump performance. FIG. 6 is a flow sheet regarding pump performance degradation. When the performance of the pump 1 decreases, the pump performance curve 21 of the block 11 decreases as shown by the dotted line. And the discharge pressure P ₀ and discharge amount Q ₀ of pump 1 are curve 43
After the performance decreases, P′ ₀ and Q′ ₀ become P ₀ > P′ ₀ , Q ₀ > Q′ ₀ and the dilute liquid flow rate Q ₁ is the pressure of the supply liquid P ₀ and the flow rate Q ₀
Due to the decrease from pressure P' ₀ to flow rate Q' ₀ , Q ₁ >Q' ₁ However, Q ₁ is the dilute liquid flow rate after the pump performance has deteriorated, and the concentrated liquid flow rate Q ₂ is mainly due to the decrease in the feed liquid, Q ₂ > Q′ ₂ However, Q′ ₂ is the concentrate flow rate after the pump performance deteriorates. Since the nozzle opening degree A _V is constant, V = Q ₂ / A _V after changing the nozzle outlet flow velocity V' decreases to V
>V', and as shown in block 17, the concentrate pressure _P'2 after the pump performance has decreased becomes _P2 >_P'2 . From the above, when P ₀ >P' ₀ and P ₂ >P' ₂ , pump 1
It is judged that the performance has deteriorated. Judgment of pump performance deterioration as an example of an indicator
Let us consider the case of calculating Q′ ₀ /Q ₀ . Since there is no fixed expression for pump performance deterioration, the above is just an example. If the pump performance deteriorates, the Q-H curve itself changes, so it cannot be determined from the Q-H curve when the pump performance is normal. Therefore, the flow rate after pump performance decreases
Assuming Q′ ₀ , it is checked to determine whether it corresponds to pressure P′ ₀ . Next, I will explain the method. The flow rate V' is determined from the concentrate pressure P' ₂ using the formula V'=α√2' ₂ or the curve 26 of block 17. Since the nozzle opening is constant, the changed concentrated liquid flow rate _Q'2 can be found from Q'=A _V V'. Assume that the discharge amount Q′ ₀ after the performance of the pump 1 has decreased. The pressure loss in the flow path after pump performance decreases is the flow rate Q ₀
Find it as a function or constant. This pressure loss
For example, P′ _L1 is 1 for pump discharge pressure 50Kg/cm ²
It has a magnitude of about ² kg/cm, and since it is a change within that range, there is no practical problem in using it as a constant. The membrane surface pressure changes to P′ _M = P′ ₀ − P′ _L1 . The concentration C′ ₂ of the concentrated liquid after the pump performance has deteriorated is determined by C′ ₂ = C ₀ ×Q′ ₀ /Q′ ₂ , and the membrane surface concentration of the feed liquid near the membrane on the supply side is
Calculate by C' _M = (C ₀ + C' ₂ )/2. The osmotic pressure π' _M after the pump performance is reduced is determined from the curve 24 representing the relationship between concentration and osmotic pressure in block 12. Thus, reverse osmosis pressure △P' is calculated from △P' = (P' _M - P ₁ ) - (π' _M - π ₁ ). When the temperature change of the supply liquid is large, use temperature detector 3.
Knowing the supply liquid temperature T, find D _W /T, and find the coefficient K' ₀ determined by the type of membrane from K' ₀ =K/(D _W /T). Calculate Q′ _0CALC =Q′ ₁ +Q′ ₂ =A _M K△P′+Q′ ₂ , compare Q′ ₀ and Q′ _0CALC , and if the error is large,
Reassume Q′ ₀ and repeat the process again. If the error between Q ₀ ′ and Q′ _0CALC is within the allowable value, calculate Q′ ₀ /Q ₀ and determine the degree of pump performance degradation. FIG. 7 is a control block diagram showing the pump performance deterioration detection device. The parts where the output end and input end of the membrane outlet pressure detector 6, concentrate flow rate calculator 6b, membrane surface concentration calculator 6c, and osmotic pressure function generator 12a are sequentially connected are shown in FIGS. 3 and 5. It has the same configuration as the control block diagram shown in FIG. 1, and the explanation of the configuration will be omitted. One input end is connected to the output end of the membrane inlet pressure detector 2, and the other input end is connected to the feed liquid flow rate setting device 46.
membrane pressure calculator 44 connected to one output end of
and a dilute liquid flow rate calculator 45, one of whose input ends is connected to the output end of the osmotic pressure function generator 12a, and the other input end is connected to the output end of the membrane surface pressure calculator 44; A feed liquid flow rate comparator 48 whose ends are respectively coupled to the output ends of the concentrated liquid flow rate calculator 6b, the dilute liquid flow rate calculator 45, and the feed liquid flow rate setting device 46, and whose input end is the output end of the feed liquid flow rate comparator 48. A feed liquid flow rate calculator 47 is connected to a feed liquid flow rate calculator 47, which is hypothetically set to a feed liquid flow rate Q' ₀ , an input end of which is connected to an output end of the feed liquid flow rate calculator 47, a feed liquid flow rate comparator 48, a membrane A pump performance controller 46 whose output ends are connected to the input ends of the surface pressure calculator 44 and the membrane surface concentration calculator 6c, respectively, and whose input ends are connected to the output ends of the feed liquid flow rate comparator 48, respectively. A deterioration degree indicator 49, a pump performance deterioration degree storage section 50 which is operated over time by a timer 51, a pump performance change over time indicator 52 whose input end is connected to the output end of the performance deterioration degree storage section 50, and a membrane inlet. The pump performance deterioration detection device is composed of a pressure detector 2, a membrane outlet pressure detector 6, a concentrate flow rate calculator 6b, a membrane surface concentration calculator 6c, and an osmotic pressure function generator 12a. Membrane outlet pressure detector 6, concentrate flow rate calculator 6b,
The control operations following the film surface concentration calculator 6c and the function generator 12a are the same as those shown in FIGS. 3 and 5, and their explanation will be omitted. When it is determined that the performance of the pump 1 has deteriorated, the feed liquid flow rate comparator 48 receives the concentrated liquid flow rate Q'2 outputted from the concentrated liquid flow rate comparator 6b, and inputs the concentrated liquid flow rate Q' ₂ outputted from the concentrated liquid flow rate comparator 6b, The discharge amount Q′ ₀ has been set and the set value has been input. The membrane surface pressure calculator 44 calculates the flow path pressure loss P' _L1 = a ₁ (Q' ₀ /QR) 2 from the discharge amount P' ₀ inputted from the membrane inlet pressure detector ² and the assumed discharge amount Q' ₀ . is calculated, and the membrane surface pressure P′ _M is output. The dilute liquid flow rate calculator 45 receives the membrane surface pressure P' _M from the membrane surface pressure calculator 44 and the osmotic pressure π' _M from the osmotic pressure function generator 12a, and calculates △P' = (P' _M - P ₁ ) − (π′ _M −π ₁ ) is calculated. Then, the dilute liquid flow rate Q' ₁ is calculated from Q' ₁ =A _M KΔP' and outputted to the supply liquid flow rate comparator 48 . The liquid supply flow rate comparator 48 calculates the assumed discharge amount.
Calculate the sum of the diluted liquid flow rate Q' ₁ calculated based on Q' ₀ and the concentrated liquid flow rate Q' ₂ calculated by the concentrated liquid flow rate calculator 6b, Q' _{0 CALC} = Q' ₁ + Q' ₂ , and △ Find Q ₀ = |Q′ ₀ −Q′ _0CALC |. Compare △Q ₀ with a predetermined allowable value β, and if △Q ₀ > β, calculate △Q ₀ and Q′ _0CALC to the liquid supply flow rate calculator 47.
The feed liquid flow rate calculator 47 calculates the reset value Q' ₀ , and if the assumption of Q' ₀ is Q' ₀ >Q' _0CALC , it resets Q' ₀ to a smaller value, and the assumption of Q' ₀ is If Q′ ₀ <Q′ _0CALC
Reset Q′ ₀ to a large value. The liquid is sent to the supply liquid flow rate setting device 46, and in the same manner, Q' 0 _CALC for the reset value Q' ₀ is determined and ΔQ ₀ is compared with β. When △Q ₀ ≦β, the calculation of Q′ ₀ /Q ₀ is performed and the value is output, inputted and displayed on the pump performance deterioration degree display 49, and also stored in the pump performance deterioration degree storage unit 50. The timer 51 periodically stores the data, and the pump performance change indicator 52 shows changes in the performance of the pump 1 over time. FIG. 8 is a control block diagram of an abnormality factor determination device for a membrane separation device. As explained above, the detected pressure _P'0 of the membrane inlet pressure detector 2, the detected pressure _P'2 of the membrane outlet pressure detector 6, the discharge pressure _P0 of the pump 1 set when the device is normal, and the concentrated liquid The pressure of P ₂
It was stated that the abnormal factors can be identified in comparison with the above. Here, we will talk about the abnormality factor discrimination device. The input end thereof is coupled to each of the output ends of the membrane inlet pressure detector 2 and the membrane inlet/outlet pressure calculation section 54,
When the input discharge pressure P′ ₀ of pump 1 and normal value P ₀ of membrane inlet pressure are P ₀ > P′ ₀ , output [1],
When P ₀ ≦P′ ₀

It has one output end 53A that outputs [0], and outputs [1] when P ₀ <P' ₀ ,
When P′ ₀ ≧P′ ₀

A membrane inlet pressure comparator 53 having another output terminal 53B that outputs [0] and having a comparator or differential amplifier circuit using, for example, an operational amplifier, a membrane outlet pressure detector 6, and a membrane inlet/outlet pressure calculation unit 54. _Its input terminal is connected _{to each} of _the output terminals of
When P ₂ ≦P′ ₂

One output terminal 5 that outputs [0]
5A, outputs [1] when P ₂ <P' ₂ , and P ₂
When ≧P′ ₂

A membrane outlet pressure comparator 55 having another output terminal 55B that outputs [0], for example, a comparator using an operational amplifier or a differential amplifier circuit, and a dilute solution flow rate setting device 56.
A membrane inlet/outlet pressure calculation unit 54 whose input end is connected to the output end of the dilute solution flow rate setting device 56, a membrane inlet pressure detector 2, a membrane outlet pressure detector 6, and one input end of which is connected to the membrane inlet pressure an AND gate 57 connected to one output end 53A of the comparator 53 and whose other input end is connected to one output end 55A of the membrane outlet pressure comparator 55; AND gate 58 coupled to one other output terminal 53B of the comparator 53 and one other input terminal coupled to one output terminal 55A of the membrane outlet pressure detector.
and an AND gate whose one input end is coupled to another output end 53B of the membrane inlet pressure comparator, and whose other input end is coupled to another output end 55B of the membrane outlet pressure comparator. 59 and and gate 5
a pump performance deterioration alarm 61 and a flow path blockage alarm 62 connected to the respective output ends of the pumps 7, 58, and 59, each having a signal voltage amplification circuit, a power control circuit, and an output driver therein and operating a display means; An abnormality factor determination device for a membrane separation apparatus is constituted by a membrane performance deterioration alarm 63 (hereinafter simply referred to as alarms 61, 62, and 63 when referred to individually). The membrane inlet/outlet pressure calculating section 54 has contents as shown in FIG. 9, for example. Figure 9 shows the diluent flow rate on the ordinate.
The pressure is shown on the abscissa with Q ₁ , curve 64 shows the Q ₁ -P ₀ curve, and curve 65 shows the Q ₁ -P ₂ curve. All of these indicate cases where the membrane separation device is normal. Horizontal diluent flow rate Q ₁ as shown in the figure
If we set the membrane inlet pressure P ₀ corresponding to that Q ₁ ,
The membrane outlet pressure P ₂ is determined. The above curves 64, 65
can be realized using a function generator. When operating with the dilute solution flow rate setter 56 set to flow rate Q ₁ , the membrane inlet/outlet pressure calculation section 54 outputs the discharge pressure P ₀ of the pump 1 and the pressure P ₂ of the concentrated liquid, which correspond to the normal state of the device. Membrane inlet pressure comparator 5
3. Input each to the membrane outlet pressure comparator 55. The pressure P′ ₀ detected by the membrane inlet pressure detector 2 is input to the membrane inlet pressure comparator 53, and the pressures P ₀ and P′ _{0 are}
are compared. If P ₀ = P' ₀ , the output ends 53A and 53B of the membrane inlet pressure comparator 53 are

Since it outputs [0], AND gates 57, 58,
59 is all

Each alarm 6 outputs [0].
1, 62, and 63 do not work. The pressure P' ₂ detected by the membrane outlet pressure detector 6 is input to the membrane outlet pressure comparator 55, and the pressures P ₂ and P' ₂ are
are compared. If P ₂ = P' ₂ , the output ends 55A and 55B of the membrane outlet pressure comparator 55 are

Since it outputs [0], AND gates 57, 58, and 59 all

Since it outputs [0], each alarm device 59, 60,
61 does not work. When P ₀ >P' ₀ in the membrane inlet pressure comparator 53, one output terminal 53A outputs [1], and the membrane outlet pressure comparator 55 outputs [1] in the case that P ₂ >P' ₂ . Since [1] is output to the two output terminals 55A, the AND gate 57 outputs [1] and activates the pump performance deterioration alarm 61 to notify that the pump performance has deteriorated. In this case, the AND gates 58 and 59 are connected to the other output terminal 53B of the membrane input pressure comparator.
from

Since [0] is included, the AND gate 58,
59 outputs

At [0], the channel blockage alarm 62 and membrane performance deterioration alarm 63 do not operate. When the membrane inlet pressure comparator 53 has P ₀ <P' ₀ , its other output terminal 53B outputs [1], and when the membrane outlet pressure comparator 55 has P ₂ >P' ₂ Since one of the output terminals 55A outputs [1], the AND gate 58 outputs [1] and operates the flow path blockage alarm 62 to notify the flow path blockage. In this case, the AND gate 57 is connected to one output terminal 53A of the membrane inlet pressure comparator.

[0] is entered,
AND gate 59 is connected to the other output end 55B of the membrane outlet pressure comparator.

Since [0] is input, AND gates 57 and 59 are

[0] is output,
Pump performance reduction alarm 61, membrane performance reduction alarm 6
3 does not work. When the membrane inlet pressure comparator 53 has P ₀ <P' ₀ , its other output terminal 53B outputs [1], and when the membrane outlet pressure comparator 55 has P ₂ <P' ₂ Since it outputs [1] to the other output terminal 55B, the AND gate 59 outputs [1] and activates the membrane performance deterioration alarm 63 to notify the membrane performance deterioration. In this case, the AND gates 57 and 58 receive the output signal of one output terminal 55A of the membrane outlet pressure comparator.

Since [0] is input, AND gate 57,
58 are each

[0] is output, and the pump performance deterioration alarm 61 and flow path blockage alarm 62 do not operate. Pump discharge pressure P ₀ , concentrate pressure P ₂ The change values P′ ₀ , P′ ₂ are explained as being determined without variation, but in reality, even under normal conditions, for example, the membrane input pressure of pump discharge pressure P ₀ The numerical value detected by the detector 2 varies within a small range. The same applies to the concentrate pressure _P2 . Pump discharge pressure in the above explanation
The equality and inequality signs between P ₀ and P′ ₀ and concentrated liquid pressure P ₂ and P′ ₂ are used to express the main points of the present invention, and in actual equipment, for example, P ₀ −P′ ₀ =△ The fluctuation range when the device is normal, which is determined by P _0C △P _0C is m, and △P _0C
It is necessary to configure the structure so that a signal is output only when P ₀ -m>P′ ₀ exceeds P 0 −m>P′ 0. In this way, the cause and extent of abnormalities such as membrane performance deterioration, channel blockage, pump performance deterioration, etc. can be determined. As a result of these, the diluent flow rate Q ₁ generally decreases. Therefore, the dilute liquid flow rate Q ₁ is corrected by determining the nozzle opening degree A _V as explained in FIG. However, for the coefficient K ₀ , the resistance coefficient a ₁ , and the discharge amount Q ₀ of the pump 1, which are determined depending on the type of membrane, corrected values are used when the membrane separator is abnormal. The present invention supplies a liquid to a semipermeable membrane using a centrifugal pump as a pressurizing means, and is equipped with a supply liquid side pressure holding means on the concentrated liquid discharge side, wherein the pump discharge side pressure and the concentrated liquid pressure are detected. Since it is equipped with a control circuit that compares the signals detected by these pressure detection means, it is possible to determine both the abnormality of the membrane separation apparatus and the cause of the abnormality. The present invention further provides that when the above-mentioned abnormality factor is determined, when the performance of the semipermeable membrane 4 is decreased, the value K′ ₀ after the membrane performance decrease of the coefficient K ₀ determined by the type of semipermeable membrane is calculated backwards, and K ₀ and Equipped with a control circuit that compares K′ ₀ , and in case of blockage of the flow path, the resistance coefficient of the flow path a ₁
It is equipped with a circuit that calculates a′ ₁ in the case of blockage of the flow path and compares a ₁ and a′, and calculates the pump discharge amount Q when the pump performance decreases, which corresponds to the pump discharge amount Q ₀ when the pump performance decreases. Since it is equipped with a control circuit that back-calculates ₀ , it is possible to know the degree of abnormality for each abnormality factor. Therefore, the timing and scale of maintenance and repair can be determined without disassembling the device. After detecting the abnormality, the coefficient K′ ₀ ,
By determining a′ ₁ and membrane surface pressure P′ _M , the signal to the pressure holding means can be corrected to maintain the dilute liquid flow rate. Note that in the above explanation, all determinations are made using pressure, but flow rate may be used instead.
This is because an increase in pump discharge pressure corresponds to a decrease in flow rate, and an increase in turbine inlet pressure corresponds to an increase in flow rate.
When using a flow rate, membrane deterioration is Q ₀ > Q′ ₀ and Q ₂ <
Q′ ₂ , and blockage of the pipeline or deterioration of pump performance is determined by Q ₀ >Q′ ₀ and Q ₂ >Q′ ₂ . As described above, the present invention is a simple device that (1) can detect a decrease in membrane performance, blockage of a flow path, and a decrease in pump performance even under different operating conditions, improving the reliability of the device. (2) It has become possible to detect the degree of the abnormality mentioned above and to understand the abnormality quantitatively. (3) The degree of the abnormality mentioned above can be detected as a change over time, which is extremely effective for operation management such as setting the timing for equipment replacement. (4) Even after an abnormality occurs, the pressure holding means is controlled with the corrected output, making it possible to provide a device with good operability.

[Brief explanation of drawings]

All drawings show embodiments of the present invention.
The figure is a flow sheet of the membrane separation device, Figure 2 is a flow sheet showing the case where the performance of the semipermeable membrane is degraded, and Figure 3 is a flow sheet showing the case where the performance of the semipermeable membrane is decreased.
The figure is a control block diagram of the membrane performance deterioration degree detection device, FIG. 4 is a flow sheet showing the determination of the degree of flow path performance deterioration, FIG. Flow sheet regarding pump performance deterioration, Fig. 7 is a control block diagram of the pump performance deterioration detection device, Fig. 8 is a control block diagram of the abnormality factor discrimination device of the membrane separation device, and Fig. 9 is the membrane inlet pressure calculation unit. FIG. 1... Pump, 2... Pressure detector, 3... Temperature detector, 4... Semipermeable membrane, 5... Flow meter, 6... Pressure detector, 7... Water turbine, 7'... Inlet nozzle , 8
... Motor, 9 ... Control device, 10 ... Flow control valve, 11, 12, 13, 15, 16, 17 ... Block, 18 ... Driver, 21, 22, 23,
24, 26, 28...Curve, 25...Line, 27...
...Characteristic curve, 29...Membrane surface pressure calculator, 30...
Dilute liquid flow rate calculator, 31... Membrane performance deterioration degree calculator, 32... Membrane performance deterioration degree indicator, 33... Membrane performance deterioration degree storage section, 34... Timer, 35... Time change indicator, 37 ...occlusion degree calculator, 38...
Occlusion degree indicator, 39... Occlusion degree storage section, 41...
Timer, 42... Time change indicator, 43... Curve, 44... Membrane surface pressure calculator, 45... Diluted liquid flow rate calculator, 46... Liquid supply flow rate setting device, 47... Liquid supply flow rate calculator , 48... liquid supply flow rate comparator, 49...
... Performance deterioration degree indicator, 50 ... Performance deterioration degree storage unit, 51 ... Timer, 52 ... Time change indicator, 53 ... Membrane inlet pressure comparator, 53A, 53B
... Output end, 54 ... Membrane inlet/outlet pressure calculation section, 55
... Membrane outlet pressure comparator, 55A, 55B ... Output end, 56 ... Dilute solution flow rate setting device, 57, 58,
59...and gate, 61,62,63...alarm, 64,65...curve.

Claims (1)

[Scope of Claims] 1. A centrifugal pump that pressurizes the supplied solution, a semipermeable membrane, a system pressure holding means disposed downstream of the semipermeable membrane on the concentrated solution side, and a control device for the system pressure holding means. In a membrane separation device that separates solutes in a solution and obtains a dilute solution and a concentrated solution, it is equipped with a means for detecting the pressure P ₀ of the solution on the pump discharge pressure side and a means for detecting the pressure of the concentrated solution.
Equipped with a means for detecting P ₂ , abnormalities in the membrane separation device can be determined based on factors by comparing the normal values of the pressures P ₀ and P ₂ of the membrane separation device with the detected values P′ ₀ and P′ ₂ , respectively. A membrane separation device characterized by being equipped with a control circuit that performs the following steps. 2 Normal pressure P ₀ , P ₂ and detected pressure P′ ₀ ,
When P′ ₂ is P ₀ < P′ ₀ and P ₂ < P′ ₂ , a signal indicating the performance degradation of the membrane is output, and when P ₀ < P′ ₀ and P ₂ > P′ ₂ , a signal is output. The abnormality determining device according to claim 1, which outputs a signal indicating a blockage of the passage, and outputs a signal indicating a decrease in pump performance when P ₀ >P' ₀ and P ₂ >P' ₂ . Equipped with a membrane separation device. 3 a centrifugal pump that pressurizes the supply solution;
Membrane separation that separates solutes in a solution and obtains a dilute solution and a concentrated solution, which is equipped with a semipermeable membrane, an internal pressure holding means disposed downstream of the semipermeable membrane on the concentrated solution side, and a control device for the internal pressure holding means. The device includes means for detecting the pressure P ₀ of the solution on the pump discharge pressure side and means for detecting the pressure P ₂ of the concentrated solution, and the normal values of the pressures P ₀ and P ₂ and the detected values P′ ₀ and P ′ ₂ , the pump discharge side pressure P′ ₀ and concentrate pressure
If the performance of the membrane deteriorates after inputting _P'2 , the coefficient K0 or the coefficient _K'0 or K' after the change in K, which represents the membrane capacity determined by the _type of membrane, is calculated backwards and the flow path is blocked. If the resistance coefficient a is the coefficient after the change of ₁
a′ ₁ is calculated backwards, and in the case of a decrease in pump performance, the discharge amount Q′ ₀ after the change in the pump discharge amount Q ₀ is calculated, and in each case, the value K ₀ or K before and after the change, K′ ₀ or K 1. An abnormality degree detection device for a membrane separation device, comprising a device for calculating the degree of abnormality by factor in the membrane separation device by comparing ′, a ₁ , a′ ₁ , Q ₀ , and Q′ ₀ . 4 When the abnormality degree detection device recited in claim 3 detects the abnormality degree for each factor, the coefficient _K'0 , the resistance coefficient _a'1 , and the semipermeable membrane supply side pressure P, which are determined by the type of membrane, respectively. An abnormality detection device for a membrane separation device, which is equipped with a control circuit that corrects a signal indicating the opening degree of a pressure holding means using _M.