JP5883754B2 - Operation planning support system - Google Patents

Description

  The present invention relates to an operation plan support system having a function of changing the amount of water produced to an appropriate value in a desalination facility using a membrane for obtaining fresh water from seawater or brine.

  In recent years, seawater desalination apparatuses and brine water desalination apparatuses that perform filtration using a semipermeable membrane tend to increase. Semipermeable membranes include reverse osmosis membranes and forward osmosis membranes depending on the structure and usage. These semipermeable membranes are made of materials such as cellulose and polyamide, and in the case of reverse osmosis membranes, by applying a pressure higher than the osmotic pressure of seawater, salt does not permeate the membrane but allows water to permeate. Fresh water can be obtained.

  For example, when seawater is used as raw water, the osmotic pressure is about 2.4 MPa, and it is common to drive the pump at a pressure more than about twice that, and the power cost accounts for a large proportion of the operating cost. Occupy. Therefore, power costs are reduced by increasing pump efficiency and using large pumps with good pump efficiency. However, these hardware measures are limited and have disadvantages such as an increase in initial cost.

JP 2009-580 A JP-A-11-33360 JP 2011-240234 A Japanese Patent Application Laid-Open No. 2011-120988

  On the other hand, the freshwater desalination performance of the semipermeable membrane described above is affected by several external conditions. For example, in the case of seawater desalination equipment, when the temperature of seawater is high, much freshwater is obtained. Moreover, when the salt concentration of seawater is high, there is little fresh water obtained. These conditions naturally vary depending on the season, but are particularly affected by weather and tides, especially when the river is near the intake of a seawater desalination facility. As a result, the power required to obtain the desired fresh water varies with time. Therefore, if it is possible to carry out an operation that produces a lot of fresh water at a time when the power required for fresh water generation is small and generates a little fresh water at a time when the power required for fresh water generation is large, the power cost can be reduced and the operation cost can be reduced. It becomes possible.

  In general, a fresh water tank is provided after the seawater desalination facility, from which fresh water is sent to the outside of the facility. If the operation is to produce a large amount of fresh water at a time when the power required for fresh water generation is small, and to generate fresh water at a time when the power required for fresh water generation is large, the fresh water tank will exceed the upper limit water level. Overflowing or falling below the lower water level. Therefore, it is necessary to set the amount of fresh water after grasping the water level (or the amount of water) of the fresh water tank.

In addition, depending on the pond area, there is a case where the electricity charge unit price varies depending on the season and time. In order to reduce the operating cost, it is also effective to produce a large amount of fresh water during a time period when the unit price of electricity is low, and to produce little fresh water during an expensive time period.
However, after considering all the water quality conditions and power unit price that will change over time in the future and the water level (or water volume) of the freshwater tank that functions as a buffer, an operation plan that will result in the lowest operating cost is formulated. It was difficult to do. In order to solve this problem, the following prior art has been proposed so far.

  Patent Document 1 describes a technique related to an operation support apparatus for a membrane filtration treatment apparatus for a water purification plant, and particularly describes that recommended operation conditions are indicated based on information such as turbidity of raw water. However, the invention described in Patent Document 1 is not intended for seawater or brine containing a large amount of salt, and cannot be used for operation support of a desalination facility. As described above, the desalination apparatus using the membrane is because the power cost is greatly affected by the change in salt concentration.

  Patent Documents 2 to 4 are all inventions targeting seawater desalination facilities. Patent Document 2 describes a technique related to an operation control device for a water production plant using a reverse osmosis membrane module, and in particular, calculates a production water volume range that can be produced based on the temperature and concentration of the supplied water. It is shown. However, in the invention described in Patent Document 2, it is not possible to make an operation plan that takes into account the unit price of electric energy that changes with time and a freshwater tank having a buffer function.

  Patent Document 3 describes a technique related to a seawater desalination apparatus that is set to appropriate operating conditions and reduces the amount of electric power. The invention described in Patent Document 3 uses seawater temperature information, but it is not possible to construct an operation plan that takes into account a freshwater tank that has a buffer function for the unit price of electric energy that changes with time.

  Patent Document 4 discloses a desalination apparatus provided with a reverse osmosis membrane apparatus. Although it is shown that the temperature of raw water is measured and fed back to the setting of operating conditions, it is not shown that an operating plan is made or that the buffer function of a fresh water tank is used effectively. Furthermore, no consideration is given to the seasonal electricity bill, and the above-mentioned problems cannot be solved.

  An object of the present invention is to provide a system that supports the formulation of an operation plan that can effectively reduce the power cost by effectively utilizing the buffer function of a fresh water tank for the water quality and the unit price of electric power that change with time. is there.

  In order to achieve the above object, the operation plan support system of the present invention provides a salt concentration prediction value of raw water in an operation plan support system for a desalination facility having a fresh water tank having a buffer function for storing fresh water produced from raw water. The salt concentration time change prediction unit for obtaining the water temperature time change prediction unit for obtaining the water temperature prediction value of the raw water, the salt concentration prediction value, the water temperature prediction value, the electricity rate unit by time of the region where the desalination equipment is installed, and the fresh water tank Fresh water tank upper limit water amount, which is the upper limit of the amount of water stored in the fresh water tank, fresh water tank lower limit water amount, which is the lower limit value of the water amount stored in the fresh water tank, fresh water in the fresh water tank, which is the amount of fresh water stored in the fresh water tank, and fresh water demand It is characterized by comprising an operation plan calculation unit that calculates a water production plan by obtaining the power cost of the desalination facility based on the amount, and a water production plan display unit that displays the calculated water production plan.

  According to the present invention, since the power cost can be reduced by a software response without an expensive hardware investment such as a high-efficiency pump or a large-scale pump, cheaper fresh water can be supplied. Furthermore, since the power itself can be reduced, not only costs but also greenhouse gas emissions can be reduced.

It is a block diagram of the driving | operation plan assistance system in Example 1 of this invention. It is a block diagram of the desalination equipment used as Example 1 of this invention. It is an example of the time change of the salt concentration in Example 1 of this invention. It is an example of the electricity bill unit price according to time in Example 1 of the present invention. It is an example of the trial calculation result in Example 1 of this invention. It is a block diagram of the driving | operation plan assistance system in Example 2 of this invention. It is a block diagram of the driving | operation plan assistance system in Example 3 of this invention. It is a block diagram of the desalination installation used as Example 3 of this invention. It is a block diagram of the driving | operation plan assistance system in Example 4 of this invention. It is a block diagram of the driving | operation plan assistance system in Example 5 of this invention.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of an operation plan support system 1 that is Embodiment 1 of the present invention, and FIG. 2 is a diagram illustrating a partial configuration of a desalination facility 6. The operation plan support system 1 according to the present embodiment is a device that makes an operation plan for the desalination facility shown in FIG.

  As shown in FIG. 2, the desalination facility 6 includes a high-pressure pump 58 that sends the raw water 62 taken into a reverse osmosis membrane device (reverse osmosis membrane) 60, a reverse osmosis membrane device 60 that generates fresh water from the raw water 62, and a reverse osmosis membrane. A power recovery device 56 that recovers the concentrated waste water 72 from the device 60 and a fresh water tank 4 that stores the fresh water 2 obtained by the reverse osmosis membrane device 60 are provided. Examples of the raw water 62 include seawater and brine. A reverse osmosis membrane device 60 is disposed on the downstream side of the high-pressure pump 58. The reverse osmosis membrane device 60 is connected to the power recovery device 56 and the fresh water tank 4. The reverse osmosis membrane device 60 is made of a material such as cellulose or polyamide. By applying a pressure equal to or higher than the osmotic pressure of the raw water 62 to the reverse osmosis membrane device 60, the salt contained in the raw water 62 does not permeate the membrane and is recovered by the power recovery device 56 as the concentrated waste water 72. Fresh water 2 that has passed through the reverse osmosis membrane device 60 is stored in the fresh water tank 4.

  As shown in FIG. 1, the operation plan support system 1 includes a salt concentration time change prediction unit 8, a water temperature time change prediction unit 10, a storage unit (memory) 11, a water level meter 9, an operation plan calculation unit 28, and a water production plan. A display unit 30 is provided.

  The salt concentration time change prediction unit 8 predicts the salt concentration time change of the raw water 62 and outputs information on the predicted salt concentration time change prediction value (salt concentration prediction value) 12 to the operation plan calculation unit 28. The salt concentration time change prediction unit 8 of the present embodiment accumulates past raw water 62 data, and predicts the salt concentration time change using the accumulated data. For example, the salt concentration time change prediction unit 8 predicts the salt concentration time change of the raw water based on data of the day before the planned date or the past several days. If the estuary of the river is not far from the intake of the desalination facility 6, the tide affects the predicted salt concentration 12. The salt concentration time change prediction unit 8 may use tidal data as an input for salt concentration prediction. FIG. 3 shows an example of the change over time in the salt concentration that changes with the tide.

  The water temperature time change prediction unit 10 predicts a time change of the water temperature of the raw water 62 and outputs information on the predicted water temperature prediction value (water temperature prediction value) 14 to the operation plan calculation unit 28. The water temperature time change prediction unit 10 according to the present embodiment accumulates past data of the raw water 62 and predicts a time change of the water temperature using the accumulated data. For example, the time change prediction unit 10 predicts a time change of the water temperature of the raw water based on data of the day before the planned date or the past several days. The water temperature time change prediction unit 10 may predict the time change of the water temperature in consideration of the weather information on the day of planning.

  The storage unit 11 includes hourly electricity rate unit price information (hourly electricity rate unit price) 16 in the area where the desalination facility 6 is installed, information on the upper limit amount of fresh water that can be stored in the fresh water tank 4 (upper limit amount of fresh water tank) 18) Information on the lower limit water amount of fresh water that needs to be stored in the fresh water tank 4 (fresh water tank lower limit water amount) 20 and information on the demand amount of fresh water (fresh water demand amount) 24 are stored. The operation plan calculation unit 28 receives information on the hourly electricity rate unit price 16, the fresh water tank upper limit water amount 18, the fresh water tank lower limit water amount 20, and the fresh water demand amount 24 from the storage unit 11.

  The water level meter 9 measures the amount of fresh water stored in the fresh water tank 4 of the desalination facility 6 in real time, and transmits information on the measured amount of fresh water to the operation plan calculation unit 28. The operation plan calculation unit 28 receives information on the amount of fresh water stored in the fresh water tank 4 from the water level gauge 9 in real time.

  Although the operation plan calculating part 28 of a present Example shows the example which calculates | requires the one water production plan 26 and displays it on the water production plan display part 30, it calculates | requires the several water production plans 26, and the water production plan display part 30 is shown. It may be displayed. When displaying a plurality of freshwater generation plans 26, the operator of the desalination facility 6 selects any one freshwater generation plan, and the freshwater selected from an input device (not shown) provided in the operation plan support system 1. Enter the plan information. The operation plan support system 1 supports the operation plan work of the desalination facility 6 based on the input fresh water generation plan.

  The hourly electricity rate unit price 16 is a system in which the electricity rate unit price is low at night when power is surplus, and the electricity rate unit price is low at noon when much power is consumed. An example of the change in the electricity bill unit price 16 by time is shown in FIG. The value of the electricity rate unit price 16 by time may change not only with the time but also with the season.

  As described above, the desalination facility 6 includes the fresh water tank 4. Corresponding to conditions that change with time, such as predicted salt concentration value 12, predicted water temperature value 14, and unit price 16 per hour, the operation plan calculation unit 28 uses this fresh water tank 4 as a buffer to determine an appropriate operation plan. This is a feature of this embodiment. The operation plan calculation is performed so that the desalination equipment 6 is not operated as much as possible or the amount of fresh water is reduced as much as possible at the time when the predicted salt concentration 12 of the raw water is high, the predicted water temperature 14 of the raw water is low, and the hourly electricity unit price 16 is high. The unit 28 obtains the desalination plan 26 of the desalination facility 6. It is desirable from the viewpoint of operating costs to operate the desalination facility 6 based on such a water production plan 26. Conversely, the operation plan is to operate the desalination facility 6 or increase the amount of fresh water as much as possible at the time when the salt concentration prediction value 12 of the raw water is low, the water temperature prediction value 14 is high, and the hourly electricity bill unit price 16 is low. The calculation unit 28 obtains a desalination plan 26 for the desalination facility 6. It is desirable from the viewpoint of operating costs that the desalination facility 6 is operated based on the obtained water production plan 26.

  However, if the amount of fresh water is excessive with respect to the fresh water demand 24, the fresh water tank 4 may overflow. Conversely, if the amount of fresh water is too small with respect to the fresh water demand 24, the fresh water tank 4 is empty. There is a possibility of becoming. In that case, supply of the fresh water 2 according to the fresh water demand 24 becomes impossible, and the performance required for the desalination facility 6 cannot be satisfied.

  Therefore, it is essential that the operation plan calculation unit 28 uses the fresh water tank upper limit water amount 18 and the fresh water tank lower limit water amount 20 as the constraint conditions, and makes a plan for the fresh water production amount using the fresh water amount 22 in the fresh water tank at the present time as an initial value. Become. Therefore, in this embodiment, the information of the fresh water tank upper limit water amount 18, the fresh water tank lower limit water amount 20, and the fresh water tank fresh water amount 22 is added to the salt concentration predicted value 12, the water temperature predicted value 14, and the hourly electricity rate unit price 16 information. In use, the operation plan calculation unit 28 calculates an appropriate water production plan 26.

  Below, the specific calculation method of the desalination plan 26 by the operation plan calculating part 28 is described. In the desalination facility 6, a condition for planning the amount of water produced every hour in the next 24 hours once a day is assumed. In addition, although an example for every hour is shown in the present embodiment, it may be calculated at different time intervals such as every 30 minutes and every 10 minutes by the same method.

Now, it is assumed that freshwater demand Q2 [m ³ / h] is given as follows for time 1, time 2, time 3,.
Time 1: Q2 [1], Time 2: Q2 [2], Time 3: Q2 [3], ..., Time 24: Q2 [24]
Further, the fresh water amount in the fresh water tank 4 at the time of planning is V [0], and the set value of the fresh water amount in the fresh water tank 4 after 24 hours is V [24]. V [24] is set to a value equal to V [0] unless there is a special reason, so that the amount of fresh water in the fresh water tank 4 is the same during daily planning, and management becomes easy.

In the first embodiment, the operation plan is equivalent to the desalination plan 26. The water production plan 26 is configured from a set value of the amount of fresh water produced in the desalination facility 6. For hour 1, hour 2, hour 3, ..., hour 24 every hour, the amount of fresh water Q1 [m ³ / h] is changed to Q1 [1], Q1 [2], Q1 [3], ... ..., Q1 [24], the purpose of this embodiment is to determine these appropriate values.

The relationship between the above-described fresh water demand Q2 [m ³ / h], the fresh water amount setting value V of the fresh water tank 4 and the fresh water amount Q1 [m ³ / h] is expressed by equation (1). Here, Σ means a sum obtained by changing time i from time 1 to time 24.
ΣQ1 [i] -ΣQ2 [i] = V [24] -V [0] (1)
When this equation (1) is transformed, the following equation (2) is obtained.
ΣQ1 [i] = ΣQ2 [i] + V [24] -V [0] (2)
In the present embodiment, the operation plan calculation unit 28 sets Q1 [i] such that the relationship represented by the expression (2) is satisfied, and in this case, the freshwater tank freshwater amount 22 exceeds the freshwater tank upper limit water amount Vmax. Calculate whether or not it falls below the lower limit water volume Vmin of the fresh water tank. The value of Q1 [i] may be set using the brute force method or the Monte Carlo method using random numbers, and is not particularly limited to these methods. As an example, the setting procedure of Q1 [i] when using the Monte Carlo method is shown below.
(a) The value of ΣQ2 [i] + V [24] −V [0] is obtained according to equation (2).
(b) Prepare 24 random numbers.
(c) The value of ΣQ2 [i] + V [24] −V [0] is distributed according to the ratio of the 24 random numbers obtained in (b) above.
(d) The allocated value is the value of Q1 [i].

Using Q1 [i] set in this way, the water amount V [i] of the fresh water tank 4 is obtained by the following equation.
V [1] = V [0] + Q1 [1] -Q2 [1] (3)
V [2] = V [1] + Q1 [2] -Q2 [2] (4)
...
V [24] = V [23] + Q1 [24] -Q2 [24] (5)

The operation plan calculation unit 28 compares these V [i] with the fresh water tank upper limit water amount Vmax and the fresh water tank lower limit water amount Vmin, and if even one of them deviates from this range, return to (b) of the above procedure. Recalculate V [i] using the random number of. When all 24 are within the range of the fresh water tank upper limit water amount Vmax and the fresh water tank lower limit water amount Vmin, the operation proceeds to the next stage, and the operation plan calculation unit 28 calculates the power cost per hour as shown below.

In the desalination facility 6 using the reverse osmosis membrane 60, the osmotic pressure π [Pa] defined by the salt concentration affects the pump power. This osmotic pressure is expressed by the following equation.
Osmotic pressure π = n × R × T (6)
Here, n is a solute molar concentration [mol / L], R is a gas constant [L · kPa / K · mol], and T is a water temperature [K]. The solute molarity n is proportional to the salt concentration. From this equation (6), it is shown that the salt concentration and the water temperature are related to the osmotic pressure, and the salt concentration predicted value 12 and the water temperature predicted value 14 described above are input here.
The required pressure Pressure [Pa] of the high-pressure pump 58 that supplies the raw water 62 to the reverse osmosis membrane 60 at a high pressure is expressed by the following equation (7) using the value of the osmotic pressure π.
Pressure = π + Jv / Lv (7)
Here, Jv is the filtration flux [m / sec], and Lv is the pure water permeability coefficient [m / sec · Pa]. The value of Jv is given by the following equation (8), where the membrane area of the reverse osmosis membrane 60 is A [m ² ].
Jv = Q1 / 3600 / A (8)
Since the amount of fresh water in one hour is Q1 [m ³ / h], if the recovery rate is α [%], the supply water amount Q [m ³ / h] supplied by the high-pressure pump 58 is expressed by the following equation (9 ).
Q = Q1 × 100 / α (9)
At this time, the pressurizing power of the high-pressure pump 58 is expressed by the following equation.
PowerPump [kWh] = 0.163 × (Q / 60) × (Pressure / 10000) / RatePump ・ ・ ・ Formula (10)
Here, RatePump: pump efficiency [-].

Of the supply water amount Q, the concentrated drainage 72 other than the fresh water amount Q1 is generally supplied to the power recovery device 56 to cover a part of the pressurization power required by the high-pressure pump 58. The flow rate Qpx [m ³ / h] of the concentrated waste water 72 supplied to the power recovery device 56 is given by the following equation (11).
Qpx = Q × (100-α) / 100 (11)
The inlet pressure Ppx [Pa] of the power recovery device 56 is a value obtained by subtracting the value of the channel resistance channelLoss [Pa] of the concentrated liquid on the primary side of the reverse osmosis membrane 60 from the required pressure Pressure of the high-pressure pump 58.
Ppx = Pressure-channelLoss (12)
Here, channelLoss: pressure loss [Pa] due to channel resistance.

Therefore, if the conversion efficiency of the power recovery device 56 is pxEfficiency [−], the power PowerRecovery [kWh] that can be recovered by the power recovery device 56 is expressed by the following equation (13).
PowerRecovery = 0.163 × (Qpx / 60) × (Ppx / 10000) × pxEfficiency (13)
From the above, the consumed power PowerConsumption [kWh] can be calculated by the following equation (14).
PowerConsumption = PowerPump-PowerRecovery (14)
By multiplying this by hourly electricity unit price UnitPrice [yen / kWh], the power cost per hour [Cost / yen] can be calculated.
PowerCost = UnitPrice × PowerConsumption ... Formula (15)
CostSum [yen] is a value obtained by integrating the power cost PowerCost [yen / h] for 24 hours. The operation plan calculation unit 28 stores the value of CostSum in the first calculation, and returns to (b) of the procedure after the second time.

  CostSum [Yen] is calculated each time, and if it is smaller than the previous CostSum, the value of CostSum is replaced with the smaller one, and Q1 [i] at that time is stored. Since this example is a Monte Carlo method, this calculation is repeated many times. As a result, it is possible to obtain an operation condition with a gradually reduced power cost regardless of the presence or absence of the local minimum point. This iterative calculation may be stopped when a preset number of iterations is reached, or may be stopped when the replacement frequency of CostSum or the change width of CostSum becomes small.

  The operation plan calculation unit 28 transmits information on the fresh water generation plan 26 thus obtained to the fresh water generation plan display unit 30. The fresh water plan display unit 30 displays the received fresh water plan 26 and is notified to the operator to support the operation plan work. By operating in this desalination plan 26, the desalination facility 6 can effectively use the freshwater tank 4 in the subsequent stage while keeping the upper limit water volume 18 and the lower limit water volume 20 of the freshwater tank 4, and minimize the power cost. Can be

  As an example, FIG. 5 shows the calculation result of the fresh water generation plan 26 that can reduce the power cost most in the case of the hourly electricity bill unit price 16 shown in FIG. Fig. 5 (a) shows the amount of water produced by the desalination facility 6 when the optimization operation is performed so that the amount of water production is constant, and Fig. 5 (b) shows the optimization operation where the amount of water production is constant. It is a figure which shows the amount of water of the freshwater tank at the time of carrying out. At least the contents shown in FIG. 5 (a) are displayed as a diagram, a table, or a numerical value on the desalination plan display unit 30. Thereby, the operator can confirm the time change of the water production amount in desalination equipment. The fresh water plan display unit 30 operates information on the fresh water tank upper limit water amount 18, information on the fresh water tank lower limit water amount 20, and information on the predicted amount of water in the fresh water tank 4 when the operation is performed with a constant fresh water amount. The information may be received from the plan calculation unit 28 and displayed. FIG. 5 (b) is an example of a diagram showing a temporal change of the predicted value of the fresh water tank upper limit water amount 18, the fresh water tank lower limit water amount 20, and the water amount in the fresh water tank 4. In this trial calculation example, it was possible to reduce the power cost by about 10% compared to the case where the amount of fresh water Q1 was constant throughout the day.

  Depending on the desalination facility 6, the amount of fresh water Q1 cannot be changed continuously, and there are cases where it is necessary to perform discrete operations such as operation / stop for each series. Further, when the rotational speed control is performed using an inverter, the inverter efficiency may differ depending on the load factor. In such a case, the constraint condition is added to the above-described operation plan calculation unit 28, and it is possible to cope with it by calculating the power cost only for the condition satisfying the condition and obtaining the minimum value. is there.

  According to the present embodiment, since the power cost can be reduced by a software response without expensive hardware investment such as a high-efficiency pump or a large-scale pump, cheaper fresh water can be supplied. Furthermore, since the power itself can be reduced, not only costs but also greenhouse gas emissions can be reduced.

  FIG. 6 is a diagram illustrating a configuration of an operation plan support system according to the second embodiment of the present invention. The operation plan support system 1 according to the present embodiment is a device that makes an operation plan for the desalination facility shown in FIG. In the present embodiment, description of the same configuration as that of the first embodiment will be omitted, and different configurations will be described in detail below.

  The operation plan support system 1 of the present embodiment includes a salt concentration time change prediction unit 8, a water temperature time change prediction unit 10, a first storage unit 11, a water level meter 9, a second storage unit 13, and a freshwater demand amount prediction unit 36. The operation plan calculation unit 28 and the fresh water generation plan display unit 30 are provided. The 1st memory | storage part 11 memorize | stores the information of the electricity rate unit price 16 classified by time, the freshwater tank upper limit water volume 18, and the freshwater tank lower limit water volume 20. FIG. The second storage unit 13 stores the weather prediction data 32 and the temperature prediction value 34.

  The operation plan calculation unit 28 receives information on the salt concentration predicted value 12 of the raw water from the salt concentration time change prediction unit 8 and receives information on the water temperature predicted value 14 of the raw water from the water temperature time change prediction unit 10. In addition, the operation plan calculation unit 28 receives information on the hourly electricity rate unit price 16, the fresh water tank upper limit water amount 18, and the fresh water tank lower limit water amount 20 from the storage unit 11. The water level meter 9 measures the amount of water in the fresh water tank 4 in real time, and transmits information on the measured amount of fresh water 22 in the fresh water tank to the operation plan calculation unit 28. The fresh water demand forecasting unit 36 obtains the fresh water demand 24 based on the weather forecast data 32 and the temperature forecast value 34. Information about the obtained freshwater demand 24 is output to the operation plan calculation unit 28.

  In the present embodiment, two storage units (first storage unit 11 and second storage unit 13) are provided, but a configuration including one storage unit (for example, storage unit 11) may be used. In the case of an operation plan support system including one storage unit, the storage unit 11 includes the hourly electricity rate unit price 16, the fresh water tank upper limit water amount 18, the fresh water tank lower limit water amount 20, the weather prediction data 32, and the predicted temperature value 34. Store information. In this case, the freshwater demand prediction unit 36 receives information on the weather prediction data 32 and the temperature prediction value 34 from the storage unit 11.

In this example, it was assumed that the hourly fresh water demand [m ³ / h] was given as follows.
Time 1: Q2 [1], Time 2: Q2 [2], Time 3: Q2 [3], ..., Time 24: Q2 [24]
Since the operation plan support system 1 of the present embodiment includes the fresh water demand prediction unit 36, the fresh water demand 24 can be obtained more appropriately. A specific method for calculating the freshwater demand 24 in the freshwater demand forecasting unit 36 will be described.

As the use of the fresh water 2 obtained by the desalination facility 6, there can be considered domestic water, industrial water, and agricultural water. Among these, the amount of industrial water used is greatly influenced by the operation plan and operation rate of the factory, while domestic water and agricultural water are greatly affected by the weather and temperature. In addition to these, there are also other influences on domestic water, such as days of the week and special days (year-end and New Year holidays), but basically the demand is higher when the weather is clear and the temperature is higher, and the demand is higher when the weather is rainy and the temperature is lower. There is less qualitative tendency.
Since this qualitative tendency cannot be expressed by a physical formula, the fresh water demand prediction unit 36 obtains the fresh water demand 24 by a technique using a multiple correlation formula. An example in which the fresh water demand prediction unit 36 calculates the fresh water demand 24 will be described.

First, the freshwater demand 24 digitizes the weather forecast data 32. For example, assign a number for each weather, such as 4 for sunny, 3 for cloudy, 2 for rain, and 1 for snow. Then, the fresh water demand 24 is obtained by statistically processing the values of coefficients C1 to C3 of the following equation so as to most closely match the data of the past fresh water demand 24 together with the information of the predicted temperature value 34.
Fresh water demand = C1 + C2 × weather + C3 × temperature As described above, by using the fresh water demand 24 obtained by the fresh water demand forecasting unit 36, it is possible to produce fresh water 2 in an amount closer to the actual demand. In addition, the unevenness and waste of the operation of the desalination facility 6 can be suppressed. As a result, the power cost can be further reduced.
According to the present embodiment, since the power cost can be reduced by a software response without expensive hardware investment such as a high-efficiency pump or a large-scale pump, cheaper fresh water can be supplied. Furthermore, since the power itself can be reduced, not only costs but also greenhouse gas emissions can be reduced.

  FIG. 7 is a diagram illustrating a configuration of an operation plan support system according to the third embodiment of the present invention, and FIG. 8 is a diagram illustrating a partial configuration of the desalination facility 6. The operation plan support system 1 according to the present embodiment is a device that makes an operation plan for the desalination facility shown in FIG. In the present embodiment, description of the same configuration as that of the first embodiment will be omitted, and different configurations will be described in detail below.

  As shown in FIG. 8, the desalination facility 6 includes a high-pressure pump 58 that sends the raw water 62 taken to a reverse osmosis membrane device (reverse osmosis membrane) 60, a reverse osmosis membrane device 60 that generates fresh water from the raw water 62, and a reverse osmosis membrane. Power recovery device 56 for recovering concentrated waste water 72 from device 60, fresh water tank 4 for storing fresh water 2 obtained by reverse osmosis membrane device 60, and water supply for supplying fresh water stored in fresh water tank 4 to distribution reservoir 38 A pump 64 is provided. The fresh water tank 4 can be used as a buffer in response to conditions that vary with time, such as the concentration of salt contained in the raw water, the temperature of the raw water, and the hourly electricity bill.

  Further, when the fresh water 2 is supplied as domestic water or agricultural water, the fresh water 2 may be once sent to the distribution reservoir 38 using the water pump 64. The distribution reservoir 38 is often made high so that it can be supplied by natural flow thereafter, and the power of the water pump 64 has a non-negligible effect on the operating cost.

As shown in FIG. 7, the operation plan support system 1 of the present embodiment includes a salt concentration time change prediction unit 8, a water temperature time change prediction unit 10, a storage unit 11, a water level meter 9, an operation plan calculation unit 28, and a water production plan. A display unit 30 and a water supply plan display unit 68 are provided. The storage unit 11 stores information on hourly electricity unit price 16, fresh water tank upper limit water amount 18, fresh water tank lower limit water amount 20, fresh water demand amount 24, reservoir upper limit water amount 40, and reservoir lower limit water amount 42. Reservoir upper limit water amount 40 is the upper limit water amount of fresh water that can be stored in reservoir 38, reservoir lower limit water amount 42 is the lower limit water amount of fresh water in reservoir 38, and fresh water amount 44 in the reservoir is distributed. This is the amount of fresh water stored in the pond 38.
The water level meter 9 measures the amount of fresh water stored in the fresh water tank 4 of the desalination facility 6 in real time, and transmits information on the measured amount of fresh water to the operation plan calculation unit 28. The operation plan calculation unit 28 receives information on the amount of fresh water stored in the fresh water tank 4 from the water level gauge 9 in real time.

The water level gauge 19 measures the amount of fresh water stored in the distribution reservoir 38 in real time, and transmits information on the measured amount of fresh water to the operation plan calculation unit 28. The operation plan calculation unit 28 receives information on the amount of fresh water stored in the distribution reservoir 38 in real time from the water level gauge 19.
The operation plan calculation unit 28 receives information on the salt concentration predicted value 12 of the raw water from the salt concentration time change prediction unit 8 and receives information on the water temperature predicted value 14 of the raw water from the water temperature time change prediction unit 10. In addition, the operation plan calculation unit 28 stores information on the hourly electricity rate unit price 16, the fresh water tank upper limit water amount 18, the fresh water tank lower limit water amount 20, the fresh water demand amount 24, the reservoir upper limit water amount 40, and the reservoir lower limit water amount 42. Receive from. The operation plan calculation unit 28 receives information on the amount of fresh water stored in the fresh water tank 4 in real time from the water level gauge 9, and receives information on the amount of fresh water stored in the distribution reservoir 38 in real time from the water level gauge 19. .

  The operation plan calculation unit 28 calculates the power cost or the operation cost of the desalination facility based on the given information, and obtains an appropriate water production plan 26 and water supply plan 66. The operation plan calculation unit 28 according to the present embodiment obtains one optimal water production plan 26 and displays it on the water production plan display unit 30, and obtains one optimal water transmission plan 66 and displays it on the water transmission plan display unit 68. Although an example is shown, a plurality of water production plans 26 and a plurality of water transmission plans 66 may be obtained and the water production plan display unit 30 and the water transmission plan display unit 68 may be displayed. When displaying a plurality of water production plans 26 and a plurality of water transmission plans 66, the operator of the desalination facility 6 selects any one of the displayed water production plans and water transmission plans and displays it in the operation plan support system 1. Information on the selected water production plan is input from an input device (not shown) provided. The operation plan support system 1 supports the operation plan work of the desalination facility 6 based on the input fresh water generation plan and water supply plan.

  An operation plan calculation unit so that the desalination equipment 6 is not operated as much as possible or the amount of fresh water is reduced at the time when the salt concentration prediction value 12 of the raw water is high, the water temperature prediction value 14 is low, and the hourly electricity bill 16 is high. 28 asks for the desalination plan 26 of the desalination facility 6. It is desirable from the viewpoint of operating costs to operate the desalination facility 6 based on such a water production plan 26. On the contrary, operation is performed so that the desalination facility 6 is operated as much as possible or the amount of fresh water is increased at the time when the salt concentration prediction value 12 of the raw water is low, the water temperature prediction value 14 is high, and the hourly electricity bill 16 is low. The plan calculation unit 28 obtains a desalination plan 26 for the desalination facility 6. It is desirable from the viewpoint of operating costs to operate the desalination facility 6 based on such a water production plan 26. In terms of the water supply pump 64, the operation plan calculation unit 28 supplies water to the desalination facility 6 so that water is not supplied as much as possible at times when the hourly electricity charges are high, but is supplied as much as possible at times when the hourly electricity charges are low. It is desirable to obtain a plan 66. It is desirable from the viewpoint of operating costs to operate the desalination facility 6 based on such a water transmission plan 66.

  However, if the amount of fresh water is excessive with respect to the amount of water supplied, the fresh water tank 4 may overflow, and if the amount of fresh water generated is too small relative to the amount of water supplied, the fresh water tank 4 may be empty. is there. If the water supply amount is excessive with respect to the freshwater demand amount 24, the distribution reservoir 38 may overflow, and if the water supply amount is too small with respect to the freshwater demand amount 24, the distribution reservoir 38 may become empty. There is sex. In that case, supply of the fresh water 2 according to the fresh water demand 24 becomes impossible, and the performance required for the desalination facility 6 cannot be satisfied.

  Therefore, the operation plan calculation unit 28 uses the upper limit water amount 40 and the lower limit water amount 42 of the reservoir as a constraint condition in addition to the upper limit amount 18 of fresh water tank and the lower limit amount 20 of fresh water tank, and the fresh water amount 22 in the fresh water tank at the present time. Then, a plan for the amount of fresh water and the amount of water delivered is made with the fresh water amount 44 in the reservoir as an initial value. In this embodiment, the information on the fresh water tank upper limit water volume 18, fresh water tank lower limit water volume 20, fresh water tank water volume, reservoir upper limit water volume 40, reservoir lower limit water volume 42, and fresh water volume 44 in the reservoir is used as salt concentration prediction value 12, water temperature prediction. In addition to the information of the value 14 and the hourly electricity rate unit price 16, an appropriate water production plan 26 and water supply plan 66 are calculated.

  Below, the concrete calculation method of the water production plan 26 and the water supply plan 66 by the operation plan calculating part 28 is described. In the desalination facility 6, a condition for planning the amount of water produced and the amount of water delivered every hour for the next 24 hours is assumed once a day. In addition, although the example for every hour is shown in a present Example, the calculation in a different time interval, such as every 30 minutes and every 10 minutes, is also possible by the same method.

Now, at the time of planning, fresh water demand Q2 [m ³ / h] is given as follows for time 1, time 2, time 3, ..., time 24 every hour .
Time 1: Q2 [1], Time 2: Q2 [2], Time 3: Q2 [3], ..., Time 24: Q2 [24]
Further, the fresh water amount in the fresh water tank 4 at the time of planning is V [0], and the set value of the fresh water amount in the fresh water tank 4 after 24 hours is V [24]. V [24] is set to a value equal to V [0] unless there is a special reason, so that the amount of fresh water in the fresh water tank 4 is the same during daily planning, and management becomes easy.

Similarly, the fresh water amount at the time of planning of the distribution reservoir 38 is VR [0], and the set value of the fresh water amount of the distribution reservoir 38 after 24 hours is VR [24]. VR [24] is set to a value equal to VR [0] unless there is a special reason, so that the amount of fresh water in the fresh water tank 4 is the same during daily planning, and management becomes easy.
The hourly fresh water quantity Q1 [m ³ / h] of the desalination facility 6 is Q1 [1], Q1 [2], Q1 [3], ..., Q1 [24], and one hour by the water pump 64 When the water flow [m ³ / h] for each unit is QR [1], QR [2], QR [3], ..., QR [24], the operation plan calculation unit 28 determines these appropriate values. This is the purpose of this embodiment.

The relationship between the fresh water demand Q2 [m ³ / h], the fresh water volume setting value V of the fresh water tank 4, the fresh water volume Q 1 [m ³ / h], and the fresh water volume VR of the distribution reservoir 38 is based on the balance of fresh water volume. It is expressed by equation (16).
ΣQ1 [i] -ΣQ2 [i] = (V [24] -V [0]) + (VR [24] -VR [0]) (16)
When this equation (16) is transformed, the following equation (17) is obtained.
ΣQ1 [i] = ΣQ2 [i] + (V [24] -V [0]) + (VR [24] -VR [0]) (17)
Further, from the balance of the amount of fresh water in the fresh water tank 4, equation (18) is established.
ΣQ1 [i] −ΣQR [i] = (V [24] -V [0]) (18)
When this equation (18) is transformed, the following equation (19) is obtained.
ΣQR [i] = ΣQ1 [i] − (V [24] -V [0]) Equation (19)
The value of ΣQR [i] is obtained by substituting ΣQ1 [i] obtained by Expression (17) here.
In this embodiment, Q1 [i] that satisfies the relationship expressed by the equation (17) and QR [i] that satisfies the relationship expressed by the equation (19) are set. In this case, the fresh water amount 22 in the fresh water tank is set. Operation plan calculation unit whether fresh water tank upper limit water amount Vmax does not exceed fresh water tank lower limit water amount Vmin, fresh water amount in distribution reservoir 44 does not exceed upper limit water amount VRmax, or lower limit water amount VRmin 28 calculates. The values of Q1 [i] and QR [i] may be set using the brute force method or the Monte Carlo method using random numbers, and are not particularly limited to these methods. As an example, the procedure for setting Q1 [i] and QR [i] by the operation plan calculation unit 28 when the Monte Carlo method is used is shown in the following procedures (a) to (h).
(a) The value of ΣQ2 [i] + (V [24] −V [0]) + (VR [24] −VR [0]) is obtained according to equation (17).
(b) Prepare 24 random numbers.
(c) ΣQ2 [i] + (V [24] -V [0]) + (VR [24] -VR [0]) value is the ratio of the 24 random numbers obtained in (b) above To distribute according to.
(d) The allocated value is the value of Q1 [i].
(e) The value of ΣQ1 [i] − (V [24] −V [0]) is obtained according to equation (19).
(f) Prepare 24 random numbers.
(g) The value of ΣQ1 [i] − (V [24] −V [0]) is distributed according to the ratio of the 24 random numbers obtained in (f) above.
(h) The allocated value is the QR [i] value.

Using Q1 [i] and QR [i] set in this way, the operation plan calculation unit 28 obtains the freshwater tank freshwater amount V [i] and the freshwater amount VR [i] in the distribution reservoir by the following equations.
V [1] = V [0] + Q1 [1] -QR [1] (20)
V [2] = V [1] + Q1 [2] -QR [2] (21)
...
V [24] = V [23] + Q1 [24] -QR [24] (22)
VR [1] = VR [0] + QR [1] -Q2 [1] (23)
VR [2] = VR [1] + QR [2] -Q2 [2] (24)
...
VR [24] = VR [23] + QR [24] -Q2 [24] (25)
The operation plan calculation unit 28 compares these V [i] with the freshwater tank upper limit water amount Vmax and the freshwater tank lower limit water amount Vmin, and compares VR [i] with the reservoir upper limit water amount VRmax and the reservoir lower limit water amount VRmin. When it deviates from this range, it returns to (b) of the said procedure, and V [i] and VR [i] are recalculated using another random number. All of V [i] in 24 hours are within the range of the fresh water tank upper limit water volume Vmax and the fresh water tank lower limit water volume Vmin, and all of VR [i] are within the range of the reservoir upper limit water volume VRmax and the reservoir lower limit water volume VRmin. If there is, the operation plan calculation unit 28 proceeds to the next stage, and calculates the power cost per hour as shown below.

First, the operation plan calculating unit 28 can obtain the power consumption PowerConsumption [kWh] to be consumed by calculating the operation cost of the reverse osmosis membrane 60 according to the above-described equations (6) to (14). In the present embodiment, the power Power Transmission [kWh] consumed by the water pump 64 needs to be added to the power cost.
PowerTransmission = 0.163 × (QR / 60) × Head / RatePump ... Formula (26)
Here, QR is the water supply amount [m ³ / h], Head is the head difference [m] during water supply, and RatePump is the pump efficiency [−].

The power cost PowerCost [yen / h] can be calculated by adding the power consumed by the water pump 64 and multiplying by the hourly electricity unit price UnitPrice [yen / kWh].
PowerCost = UnitPrice × (PowerConsumption + PowerTransmission) ・ ・ ・ Formula (27)

CostSum [yen] is a value obtained by integrating the power cost PowerCost [yen / h] for 24 hours. The operation plan calculation unit 28 stores the value of CostSum in the first calculation, and returns to (b) of the procedure after the second time. CostSum [yen] is calculated each time, and if the value is smaller than the previous CostSum, the value of CostSum is replaced with the smaller one, and the operation plan calculation unit 28 stores Q1 [i] at that time. Since this example is a Monte Carlo method, this calculation is repeated many times. As a result, it is possible to obtain an operation condition with a gradually reduced power cost regardless of the presence or absence of the local minimum point. This iterative calculation may be stopped when a preset number of iterations is reached, or may be stopped when the replacement frequency of CostSum or the change width of CostSum becomes small.

  The operation plan calculation unit 28 transmits the water production plan 26 thus obtained to the water production plan display unit 30 and transmits the water supply plan 66 to the water supply plan display unit 68. The water production plan display unit 30 displays the water production plan 26 and the water transmission plan display unit 68 displays the water transmission plan 66, whereby the water production plan 26 and the water transmission plan 66 are transmitted to the operator, and the operation planning work is supported. . By operating with the fresh water generation plan 26 and the water supply plan 66, the desalination facility 6 operates effectively while maintaining the range of the fresh water tank upper limit water volume 18 and the fresh water tank lower limit water volume 20 of the fresh water tank 4, and reduces the power cost. Can be minimized. Further, the water supply pump 64 can be operated effectively while keeping the range of the upper limit water amount 40 and the lower limit water amount 42 of the downstream reservoir 38.

  According to the present embodiment, since the power cost can be reduced by a software response without expensive hardware investment such as a high-efficiency pump or a large-scale pump, cheaper fresh water can be supplied. Furthermore, since the power itself can be reduced, not only costs but also greenhouse gas emissions can be reduced.

  FIG. 9 is a diagram illustrating a configuration of an operation plan support system according to the fourth embodiment of the present invention. The operation plan support system 1 according to the present embodiment is a device that makes an operation plan for the desalination facility shown in FIG. In the present embodiment, description of the same configuration as that of the first embodiment will be omitted, and different configurations will be described in detail below.

  As shown in FIG. 9, the operation plan support system 1 of the present embodiment includes a salt concentration time change prediction unit 8, a water temperature time change prediction unit 10, a storage unit 11, a water level meter 9, an operation plan calculation unit 28, and a fresh water generation plan. A display device 30 is provided. The storage unit 11 stores information on the electricity price unit by time 16, the fresh water tank upper limit water amount 18, the fresh water tank lower limit water amount 20, the fresh water demand amount 24, the residual salt concentration allowable value 46, and the salt concentration 70 in the fresh water tank.

  The operation plan calculation unit 28 receives information on the salt concentration predicted value 12 of the raw water from the salt concentration time change prediction unit 8 and receives information on the water temperature predicted value 14 of the raw water from the water temperature time change prediction unit 10. In addition, the operation plan calculation unit 28 stores information on the electricity price unit by time 16, the fresh water tank upper limit water amount 18, the fresh water tank lower limit water amount 20, the fresh water demand amount 24, the residual salt concentration allowable value 46, and the salt concentration 70 in the fresh water tank. Received from part 11. The water level meter 9 measures the amount of fresh water stored in the fresh water tank 4 of the desalination facility 6 in real time, and transmits information on the measured amount of fresh water to the operation plan calculation unit 28.

  The operation plan calculation unit 28 receives information on the amount of fresh water stored in the fresh water tank 4 from the water level gauge 9 in real time.

  The operation plan calculation unit 28 calculates a power cost or an operation cost of the desalination facility based on the given information, and finds an appropriate water production plan 26. The operation plan calculation unit 28 according to the present embodiment obtains one optimal water production plan 26 and displays it on the water production plan display unit 30, and obtains one optimal water transmission plan 66 and displays it on the water transmission plan display unit 68. Although an example is shown, a plurality of water production plans 26 and a plurality of water transmission plans 66 may be obtained and the water production plan display unit 30 and the water transmission plan display unit 68 may be displayed. When displaying a plurality of water production plans 26 and water transmission plans 66, the operator of the desalination facility 6 selects any one of the displayed water production plans and water transmission plans, and is provided in the operation plan support system 1. The information on the selected water production plan is input from the input device (not shown). The operation plan support system 1 supports the operation plan work of the desalination facility 6 based on the input fresh water generation plan and water supply plan.

  The desalination facility 6 includes a fresh water tank 4 at the subsequent stage. Corresponding to conditions that change with time, such as the predicted salt concentration of raw water 12, predicted water temperature 14 of raw water, and unit price 16 per hour, the fresh water tank 4 is used as a buffer, and the operation plan calculation unit 28 operates appropriately. The feature of this embodiment is to obtain a plan.

  The operation plan calculation is performed so that the desalination equipment 6 is not operated as much as possible or the amount of fresh water is reduced as much as possible at the time when the predicted salt concentration 12 of the raw water is high, the predicted water temperature 14 of the raw water is low, and the hourly electricity unit price 16 is high. The unit 28 obtains the desalination plan 26 of the desalination facility 6. It is desirable from the viewpoint of operating costs to operate the desalination facility 6 based on such a water production plan 26. On the contrary, the salt concentration prediction value 12 of the raw water is low, the water temperature prediction value 14 of the raw water is high, and the desalination facility 6 is operated as much as possible at the time when the hourly electricity bill unit price 16 is low. The operation plan calculation unit 28 obtains a desalination plan 26 for the desalination facility 6. It is desirable from the viewpoint of operating costs to operate the desalination facility 6 based on such a water production plan 26.

  However, if the amount of fresh water is excessive with respect to the fresh water demand 24, the fresh water tank 4 may overflow, and if the amount of fresh water is too small with respect to the fresh water demand 24, the fresh water tank 4 becomes empty. There is a possibility. In that case, supply of the fresh water 2 according to the fresh water demand 24 becomes impossible, and the performance required for the desalination facility 6 cannot be satisfied. Therefore, the operation plan calculation unit 28 uses the fresh water tank upper limit water amount 18 and the fresh water tank lower limit water amount 20 as constraint conditions, and drafts a fresh water production plan using the fresh water tank internal fresh water amount 22 as an initial value.

  Further, in the desalination facility 6, the salt concentration remaining in the fresh water 2 may be a problem. In particular, as in the case of industrial water, depending on the application, if this salt concentration is too high, the product or piping may be damaged. In such a case, the operation plan calculation unit 28 considers the fresh water quality in the fresh water generation plan 26.

The salt concentration TDS [mol / m ³ ] contained in the fresh water 2 is affected by the quality of the feed water and the filtration flux Jv.

TDS = Js / Jv ... Formula (28)
Here, Js is a solute permeation flux [mol / (m ² · sec)], and Jv is a filtration flux [m / sec]. The solute permeation flux Js is given by the following equation (29).
Js = Ps × (Cm-Cp) ... Formula (29)
Here, Ps is the solute permeability coefficient [m / sec], Cm is the salt ion concentration [mol / m ³ ] on the membrane surface, and Cp is the salt ion concentration [mol / m ³ ] of the permeated water.

The salt ion concentration Cm [mol / m ³ ] on the membrane surface may give a predicted salt concentration 12 of the feed water, or a concentration polarization phenomenon may actually occur. good. On the other hand, the salt ion concentration Cm [mol / m ³ ] of the permeated water is sufficiently lower than that of the supplied water, and the concentration polarization is considered to be small. The values of TDS obtained by these equations (29) and (28) are Jv functions that may be different every hour. Therefore, the salt concentration of the fresh water 2 desalinated by the reverse osmosis membrane 60 may vary every hour. The fresh water tank 4 is provided at the subsequent stage of the reverse osmosis membrane 60, but the fresh water 2 filtered by the reverse osmosis membrane 60 is mixed with the fresh water 2 remaining in the fresh water tank 4, and is averaged at the outlet of the fresh water tank 4. The fresh water 2 having the salt concentration is discharged.

The salt concentration in the fresh water tank 4 at the time of planning is C [0]. Assuming that the salt concentration in the fresh water 2 filtered by the reverse osmosis membrane 60 every hour is TDS [i], the average salt concentration C [i] in the fresh water tank 4 is obtained as follows.
C [1] = (C [0] × V [0] + TDS [1] × Q1 [1] -C [0] × Q2 [1]) / (V [0] + Q1 [1] -Q2 [ 1])
... Formula (30)
C [2] = (C [1] × V [1] + TDS [2] × Q1 [2] -C [1] × Q2 [2]) / (V [1] + Q1 [2] -Q2 [ 2])
... Formula (31)
...
C [24] = (C [23] × V [23] + TDS [24] × Q1 [24] -C [23] × Q2 [24]) / (V [23] + Q1 [24] -Q2 [ twenty four])
... Formula (32)
Below, the specific calculation method of the fresh water generation plan 26 by the operation plan calculating part 28 is described. In the desalination facility 6, a condition for planning the amount of water produced every hour in the next 24 hours once a day is assumed. In addition, although the example for every hour is shown in this Example, the calculation in a different time step, such as every 30 minutes and every 10 minutes, is also possible by the same method.

Suppose that the hourly freshwater demand [m ³ / h] is given as follows at the time of planning.
Time 1: Q2 [1], Time 2: Q2 [2], Time 3: Q2 [3], ..., Time 24: Q2 [24]
Further, the fresh water amount in the fresh water tank 4 at the time of planning is V [0], and the set value of the fresh water amount in the fresh water tank 4 after 24 hours is V [24]. If the amount of fresh water per hour [m ³ / h] is Q1 [1], Q1 [2], Q1 [3], ..., Q1 [24], it is important to determine these appropriate values. This is the purpose of the example.
The relationship between the above-described fresh water demand Q2 [m ³ / h], the fresh water amount setting value V of the fresh water tank 4, and the fresh water amount Q1 [m ³ / h] is expressed by the following equation (33). Here, Σ means a sum obtained by changing time i from time 1 to time 24.
ΣQ1 [i] -ΣQ2 [i] = V [24] -V [0] (33)
When this equation (33) is transformed, the following equation (34) is obtained.
ΣQ1 [i] = ΣQ2 [i] + V [24] -V [0] (34)
In the present embodiment, the operation plan calculation unit 28 sets Q1 [i] such that the relationship represented by the equation (34) is satisfied, and in this case, the freshwater tank freshwater amount 22 exceeds the freshwater tank upper limit water amount Vmax. It is evaluated whether or not it falls below the lower limit water amount Vmin of the fresh water tank and whether the average salt concentration in the fresh water tank 4 exceeds the allowable residual salt concentration value 46TDSmax. The value of Q1 [i] may be set using the brute force method or the Monte Carlo method using random numbers, and is not particularly limited to these methods. As an example, the setting procedure of Q1 [i] when using the Monte Carlo method is shown below.
(a) The value of ΣQ2 [i] + V [24] −V [0] is obtained according to equation (2).
(b) Prepare 24 random numbers.
(c) The value of ΣQ2 [i] + V [24] −V [0] is distributed according to the ratio of the 24 random numbers obtained in (b).
(d) The allocated value is the value of Q1 [i].

Using Q1 [i] set in this way, the water amount V [i] of the fresh water tank 4 is obtained by the following equations (35) to (37).
V [1] = V [0] + Q1 [1] -Q2 [1] (35)
V [2] = V [1] + Q1 [2] -Q2 [2] (36)
...
V [24] = V [23] + Q1 [24] -Q2 [24] ... Formula (37)

Further, the operation plan calculation unit 28 calculates the average salt concentration C [i] in the fresh water tank 4 according to the equation (30) to the equation (32). The operation plan calculation unit 28 compares these V [i] with the fresh water tank upper limit water amount Vmax, the fresh water tank lower limit water amount Vmin, and the salt concentration with respect to TDSmax which is the residual salt concentration allowable value 46, and even one unit deviates from this range. If so, return to (b) of the above procedure and recalculate V [i] and C [i] using another random number. If all 24 are within the range of the fresh water tank upper limit water amount Vmax, fresh water tank lower limit water amount Vmin, and salt concentration, the residual salt concentration allowable value 46TDSmax, the process proceeds to the next stage, and the power cost per hour is calculated.

  The power cost by the reverse osmosis membrane 60 can be obtained from the above formulas (6) to (15). CostSum [yen] is a value obtained by integrating the power cost PowerCost [yen / h] for 24 hours. The operation plan calculation unit 28 stores the value of CostSum in the first calculation, and returns to (b) of the procedure after the second time. The operation plan calculation unit 28 calculates CostSum [yen] each time, and if the value is smaller than the previous CostSum, replaces the value of CostSum with the smaller one and stores Q1 [i] at that time. Since this example is a Monte Carlo method, this calculation is repeated many times. As a result, it is possible to obtain an operation condition with a gradually reduced power cost regardless of the presence or absence of the local minimum point. This iterative calculation may be stopped when a preset number of iterations is reached, or may be stopped when the replacement frequency of CostSum or the change width of CostSum becomes small.

  The operation plan calculation unit 28 transmits information on the fresh water generation plan 26 thus obtained to the fresh water generation plan display unit 30. The fresh water plan display unit 30 displays the received fresh water plan 26 and is notified to the operator to support the operation plan work. By operating in this desalination plan 26, the desalination facility 6, while keeping the conditions of the fresh water tank upper limit water amount 18 and fresh water tank lower limit water amount 20 of the subsequent fresh water tank 4, and the residual salt concentration allowable value 46, Operation that minimizes the power cost can be realized.

  According to the present embodiment, since the power cost can be reduced by a software response without expensive hardware investment such as a high-efficiency pump or a large-scale pump, cheaper fresh water can be supplied. Furthermore, since the power itself can be reduced, not only costs but also greenhouse gas emissions can be reduced.

  FIG. 10 is a diagram illustrating a configuration of an operation plan support system according to the fifth embodiment of the present invention. The operation plan support system 1 according to the present embodiment is a device that makes an operation plan for the desalination facility shown in FIG. In the present embodiment, description of the same configuration as that of the first embodiment will be omitted, and different configurations will be described in detail below.

  The operation plan support system 1 of the present embodiment includes a salt concentration time change prediction unit 8, a water temperature time change prediction unit 10, a first storage unit 11, a water level meter 9, a second storage unit 15, and a fresh water consumption actual value acquisition. Unit 48, fresh water additional required amount calculation unit 54, operation plan calculation unit 28, and fresh water production plan display device 30. The storage unit 11 stores information on hourly electricity rate unit price 16, fresh water tank upper limit water volume 18, and fresh water tank lower limit water volume 20. The storage unit 15 stores information on the freshwater demand amount 24. In the present embodiment, two storage units (first storage unit 11 and second storage unit 15) are provided, but a configuration having one storage unit (for example, storage unit 11) may be used. In the case of an operation plan support system including one storage unit, the storage unit 11 stores information on hourly electricity rate unit price 16, fresh water tank upper limit water amount 18, fresh water tank lower limit water amount 20, and fresh water demand amount 24. In this case, the fresh water additional requirement calculation unit 54 receives information on the fresh water demand 24 from the storage unit 11.

  The operation plan calculation unit 28 receives information on the salt concentration predicted value 12 of the raw water from the salt concentration time change prediction unit 8 and receives information on the water temperature predicted value 14 of the raw water from the water temperature time change prediction unit 10. In addition, the operation plan calculation unit 28 receives information on the hourly electricity rate unit price 16, the fresh water tank upper limit water amount 18, and the fresh water tank lower limit water amount 20 from the storage unit 11. The water level meter 9 measures the amount of fresh water stored in the fresh water tank 4 of the desalination facility 6 in real time, and transmits information on the measured amount of fresh water to the operation plan calculation unit 28. The operation plan calculation unit 28 receives information on the amount of fresh water stored in the fresh water tank 4 from the water level gauge 9 in real time. The fresh water additional required amount calculation unit 54 calculates the fresh water additional required amount 52 based on the fresh water consumption actual value 50 and the fresh water demand 24 value. The fresh water consumption actual value 50 is measured by the fresh water consumption actual value acquisition unit 48. The operation plan calculation unit 28 receives the fresh water additional requirement 52 from the fresh water additional requirement calculation unit 54.

  As the operation plan or desalination plan 26 of the desalination facility 6, for example, a plan for the next 24 hours may be formulated first every morning. At that time, the freshwater demand 24 for the next 24 hours is predicted and the operation is started, but the actual freshwater demand 24 does not necessarily match the predicted value. As a result, even if the operation plan formulated first in the morning is optimal at that time, it may become a non-optimal plan before 24 hours elapse. For example, if the total amount of freshwater demand 24 is not determined, the freshwater demand 24 predicted in the morning and the actual freshwater consumption actual value 50 may deviate due to changes in weather and temperature. In that case, the fresh water additional required amount calculation unit 54 calculates an operation plan calculation by calculating a fresh water additional required amount 52 required in the future with respect to the initially assumed fresh water demand 24 based on the fresh water consumption actual value 50. By giving to the unit 28, the operation plan calculation unit 28 can formulate a fresh water production plan 26 that is more realistic.

  As one method of calculating the fresh water additional requirement 52, the ratio of the fresh water demand 24 and the fresh water consumption actual value 50 is calculated, and a value obtained by multiplying the ratio by the future fresh water demand 24 is calculated as the fresh water additional requirement 52. There is a method of giving to the operation plan calculation unit 28 as follows.

  On the other hand, when the total amount in 24 hours is determined as the fresh water demand 24, an operation plan calculation unit performs a calculation for appropriately allocating the fresh water demand 24 obtained by subtracting the actual fresh water consumption value 50 from the total amount in the remaining time. 28, it becomes possible to devise a more appropriate water production plan 26, and the operator who has obtained the information in the water production plan display unit 30 also carries out an appropriate operation according to the demand side situation change. be able to.

  According to the present embodiment, since the power cost can be reduced by a software response without expensive hardware investment such as a high-efficiency pump or a large-scale pump, cheaper fresh water can be supplied. Furthermore, since the power itself can be reduced, not only costs but also greenhouse gas emissions can be reduced.

Operation planning support system 1
Fresh water 2
Fresh water tank 4
Desalination facilities 6
Salt concentration time change prediction unit 8
Water temperature / time change prediction unit 10
Storage unit 11
Predicted salt concentration 12
Storage unit 13
Predicted water temperature 14
Electricity unit price by time 16
Maximum freshwater tank volume 18
Freshwater tank lower limit water volume 20
Freshwater volume in freshwater tank 22
Freshwater demand 24
Desalination plan 26
Operation plan calculation unit 28
Water production plan display section 30
Weather forecast data 32
Predicted temperature 34
Freshwater demand forecast part 36
Reservoir 38
Reservoir upper limit water volume 40
Reservoir water limit lower limit 42
44 freshwater in the reservoir
Residual salt concentration tolerance 46
Fresh water consumption results value acquisition unit 48
Fresh water consumption results 50
Additional freshwater requirement 52
Freshwater additional requirement calculator 54
Power recovery device 56
High pressure pump 58
Reverse osmosis membrane 60
Raw water 62
Water pump 64
Water supply plan 66
Water supply plan display section 68
Salt concentration in freshwater tank 70
Concentrated drainage 72

Claims (4)

In the operation plan support system for a desalination facility having a fresh water tank having a buffer function for storing fresh water produced from raw water,
A salt concentration time change prediction unit for obtaining a salt concentration prediction value of the raw water;
A water temperature time change prediction unit for obtaining a water temperature prediction value of the raw water;
The salt concentration prediction value, the water temperature prediction value, the unit price of electricity per hour in the area where the desalination facility is installed, the fresh water tank upper limit water amount that is the upper limit value of the amount of water stored in the fresh water tank, and the fresh water tank Based on the lower limit of the fresh water tank, which is the lower limit of the amount of water, the amount of fresh water in the fresh water tank, which is the amount of fresh water stored in the fresh water tank, and the demand for fresh water, the power cost of the desalination equipment is determined to determine the desalination plan. An operation plan calculation unit to calculate,
A water production plan display unit for displaying the calculated water production plan;
In addition to the predicted salt concentration value, the predicted water temperature value, the unit price of electricity per time, the fresh water amount in the fresh water tank, the fresh water demand amount, the operation plan calculation unit is connected to the downstream side of the fresh water tank. Calculate the desalination plan by obtaining the power cost of the desalination facility based on the upper limit water volume of the reservoir, the lower limit water volume of the reservoir, and the fresh water quantity indicating the fresh water amount in the reservoir. Operation planning support system characterized by   The operation plan support system according to claim 1, further comprising a fresh water demand amount prediction unit that obtains the fresh water demand amount based on weather prediction data and a predicted temperature value. The operation plan calculator is
Residual salt concentration in fresh water in addition to the predicted salt concentration value, predicted water temperature value, unit price of electricity by time, fresh water amount in fresh water tank, fresh water demand, fresh water tank upper limit water amount and fresh water tank lower limit water amount The operation plan support system according to claim 1 or 2 , wherein a water production plan is calculated by obtaining a power cost of the desalination facility based on an allowable value and a salt concentration in the fresh water tank. A fresh water consumption actual value acquisition unit that captures the actual value of fresh water consumption;
A fresh water additional requirement calculation unit for subtracting the fresh water consumption actual value from the value of the fresh water demand, and calculating the additional amount of fresh water that needs to be freshened by adding,
Calculate the power cost based on the predicted salt concentration value, the predicted water temperature value, the electricity price unit by time, the fresh water tank upper limit water amount, the fresh water tank lower limit water amount, the fresh water amount in the fresh water tank, and the fresh water additional required amount. An operation plan calculation unit that calculates the fresh water generation plan in real time,
The operation plan support system according to any one of claims 1 to 3, further comprising a fresh water plan display unit that displays the calculated fresh water plan.