JPH0424084B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a filtration device in which a plurality of filters having different liquid passage times are arranged in parallel between an inlet main pipe and an outlet main pipe.

[Prior art]

For example, a pre-coat type filtration device is used as a filtration device for filtering condensate at a thermal power plant or a nuclear power plant. This pre-coated filtration device is
Impurities are removed by passing the treated stock solution through the filter material formed on the surface of the filter cloth in the filter. When the amount of raw solution to be treated is large and the treatment is to be performed continuously, multiple filters with a capacity smaller than the amount to be treated are installed, and each filter is operated at different times. is normal. 1st
The figure shows a schematic system of such a filtration device used in thermal power plants and nuclear power plants.

The inlet branch pipe 12 connected to the inlet main pipe 10 in FIG. 1 is provided with a flow meter 14 and an inlet valve 16, and is connected to the filter 20A via a filter inlet pipe 18. One end of a filter outlet pipe 22 is connected to the outlet of the filter 20A, and the other end of the filter outlet pipe 22 is connected to a flow rate control valve 24.
and an outlet valve 26 are connected to an outlet branch pipe 28, which communicates with an outlet main pipe 30. moreover,
A differential pressure detection tube 32 is connected between the inlet and outlet sides of the filter 20A, that is, between the filter inlet pipe 18 and the filter outlet pipe 22, and the differential pressure gauge 34 is connected to the filter 20A.
It is provided in parallel with 0A. Note that numerals 36 and 38 shown in the figure are differential pressure gauge main valves provided on the inlet and outlet sides of the differential pressure gauge 34, respectively.

N filtration series having the above-described structure are provided, and filters 20A, 20B, . . . 20N are arranged in parallel between the inlet main pipe 10 and the outlet main pipe 30. The processed stock solution transferred from the higher pressure upstream system through the inlet main pipe 10 enters the inlet branch pipe 12, passes through the flow meter 14 and the inlet valve 16, and then flows from the filter inlet pipe 18 to the filter. 20A, 20
B,...enters within 20N. The treated stock solution purified in each of these filters enters the outlet branch pipe 26 from the filtration outlet pipe 22 via the flow rate control valve 24 and the outlet valve 26 as a processing liquid, and is collected in the outlet main pipe 30. In operation of each of these filters, the difference between the pressure on the inlet side of the filter and the pressure on the outlet side of the filter is measured using a differential pressure gauge 34.
This is done by detecting the differential pressure and confirming that the differential pressure is maintained below a predetermined set value.

The filter differential pressure used to monitor the operation of each filter varies depending on the amount of impurities captured in the filter media layer.
As shown in the figure, there is a tendency to increase as the processing time, that is, the liquid passage time becomes longer. As described above, in the above-mentioned filtration device, in order to enable continuous operation of the filtration device, each filter 20
A, 20B, . . . 20N were started at equal intervals, and the operating time of each filter was varied. For example, as shown in Fig. 2, when the operating times of N filters are arithmetical like T _A , T _B , T _C ...T _N , the differential pressure of each filter is ΔP _A ,
ΔP _B , ΔP _C ...distributed as ΔP _N. Then, the filter differential pressure ΔP _N is the limit differential pressure ΔP _MAX for filtration processing.
When this is reached, the operation of this filter is stopped and a new filtration layer is precoated. The operating time T _MAX of the filter that reaches this ΔP _MAX is the maximum operating time of the filter. In this way, when operating a filtration device that has multiple filters with different filter pressures, it is assumed that the amount of treated stock solution distributed to each filter is approximately equal to the loss caused by the piping and valve configurations surrounding the filter. Then, the differential pressure including the filters in each series is kept constant.

FIG. 3 shows the relationship between the flow rate and the differential pressure for each series under such an operating method. In Figure 3, the curve showing the relationship between the flow rate and differential pressure of piping and valves shows the change in differential pressure with respect to flow rate when the configuration of piping and valves, etc. for each series is the same. The differential pressure due to piping and valves when flow rate Q is _NOR is ΔP ₁
becomes. Similarly to the above, the curves A, B, C...N show the relationship between the flow rate and the differential pressure of the filtration system having filters with different operating times. The filter shown by curve N has the shortest operating time, and the filter shown by curve N has the longest operating time.

If the rated throughput Q _NOR of the raw solution to be treated is equally supplied to each train, the differential pressure in the train represented by curve N will become abnormally large, making it difficult to operate the filter. Therefore, if the filtration device is operated by adjusting the flow rate supplied to each series so that the differential pressure of each series becomes the preset ΔP ₂ , the maximum operating time shown by curve A as shown in Figure 3 is There is a large difference between the flow rate Q _1MAX of the series including the filter with the shortest operating time and the flow rate Q _1MIN of the series including the filter with the longest operating time shown by curve N. For example, the main pipe differential pressure is 25
In the case of general condensate filtration equipment that is operated at around Kg/ ^cm2 , the deviation between the maximum flow tower (the filter to which the maximum flow is supplied) and the minimum flow tower determines the flow rate of the raw solution in the operating filter. This results in a difference of 50 to 60% from the rated throughput Q _NOR divided by the number. For this reason, the filtration speed, which influences the performance of the filter, differs due to a large imbalance in the treated stock solution supplied to each series, which is not preferable. Therefore, in order to avoid such drawbacks, it is necessary to adjust the supply amount of the treated stock solution so that the filters in each system can operate within the optimal filtration rate range, and an equal flow rate control device is set in the filtration device. . This equal flow rate control device adjusts the flow rate by adjusting the opening of the flow rate control valve shown in FIG. 1, and its flow rate control circuit is shown in FIG. 4.

Note that the filtration rate here refers to the rate of the treated stock solution passing through the filter medium layer, and is derived from the following equation.

Filtration rate = filter stock solution throughput/filter layer surface layer (m/
H) Opening degree indicator 40 provided in each series in Fig. 4
A, 40B...40N are flow rate control valves 24 of each series.
indicates the opening degree. And each opening indicator 4
The output signals of 0A, 40B, . . . , 40N are input to the comparator 42. This comparator 42 uses an opening indicator 40A, a tournament method, etc., for example.
The flow rate control valve 24 is determined based on the opening degree of the flow rate control valve 24 from 40B...40N and the flow rate of the processing stock solution flowing through each series.
The series that should have the maximum opening degree is selected and sent to the opening degree calculator 44. The opening degree calculator 44 calculates the opening degree of the flow control valve 24 whose opening degree should be maximized, and
The flow rate control valve 2 of the other system is
4 is calculated and sent to the controller 46. The controller 46 inputs an opening signal to the opening indicators so that the opening setting signal obtained from the function generator 48 is gradually transmitted to the opening indicators 40A, 40B, . . . 40N. These opening indicators 40A, 40B...40N are
In addition to receiving the signal from the controller 46, the flow rate of the treated stock solution from the flow meter 14 is received via the transmitter 50, and is sent to the exchanger 52 as an opening signal for the flow rate control valve 24.
Enter. Note that the signal from the opening indicator is input to the converter 52 via a temporary delay calculator 54 in order to prevent valve hunting caused by sudden adjustment of the opening of the flow rate control valve 24. It's getting old. The converter 52 converts the electrical signal from the opening indicator into an air signal for adjusting the opening of the flow control valve 24, and adjusts the flow rate control valve 24 of each series so that the differential pressure of each series becomes ΔP ₂ . Adjust the opening.

However, in recent years in thermal power plants and nuclear power plants, the number of filters has increased as the plant output has increased, and the conventional flow rate control method has the following drawbacks.

(1) As the number of trains increases, the control circuit that adjusts the valve opening between each train becomes complicated.

(2) In thermal power plants and nuclear power plants, because they are installed in condensate systems, there is a risk that all flow control valves will be closed due to a failure in a part of the control system.
There is a risk of plant shutdown.

(3) Installing a flow control valve requires securing space for installing the valve, complicating the piping configuration and control circuit.
This is a cause of high costs.

[Purpose of the invention]

The present invention has been made in order to eliminate the drawbacks of the prior art, and an object of the present invention is to provide a filtration device that can easily control the supply of treated stock solution to each filter.

[Summary of the invention]

The present invention provides an inlet main pipe for guiding a treatment stock solution, an outlet main pipe for collecting purified treatment liquid, and a liquid flow time period arranged in parallel via a branch pipe between the inlet main pipe and the outlet main pipe. a plurality of filters having different filters, an inlet valve provided on the inlet main pipe side of the branch pipe from the filter, and an outlet valve provided on the outlet main pipe side of the branch pipe from the filter. In the filtration device, each branch pipe is provided with a pipe loss generator such as an orifice or a throttle valve that independently increases the differential pressure as the fluid flow rate increases, so as to relatively reduce the pressure loss of the filter. The structure is such that the flow rate to each filter can be easily adjusted.

[Embodiments of the invention]

Preferred embodiments of the filtration device according to the present invention will be described in detail with reference to the accompanying drawings. Note that the same reference numerals are given to the parts corresponding to the parts explained in the prior art, and the explanation thereof will be omitted.

FIG. 5 is an explanatory diagram of an embodiment of the filtration device according to the present invention. In FIG. 5, each filter 20A, 20B...20N
The inlet branch pipe 12 leading to
is provided. Furthermore, the flow rate control valve 24 provided in the filter outlet pipe 22 and the control system shown in FIG. 4 described in the prior art are omitted.

The operation of the embodiment configured as described above is as follows. The treated stock solution led to the inlet main pipe 10 flows into the inlet branch pipe 12, and passes through the flow meter 14 and the inlet valve 16.
and filter inlet pipe 1 via orifice 56
8 into each filter 20A, 20B...20N. The treated stock solution that has flowed into each of the filters 20A, 20B...20N is purified in each filter, and then enters the outlet branch pipe 28 from the filter outlet pipe 22 via the outlet valve 26, and enters the outlet main pipe 30. be gathered at. On the other hand, each filter 20A, 20B...20
The operating state of N is monitored by detecting the differential pressure of each filter using a differential pressure gauge 34 provided in parallel with each filter, as in the prior art.

In the flow of each of these series, since the treated stock solution passes through the orifice 56, the differential pressure due to loss due to piping, valves, and orifices increases compared to the conventional method, and the differential pressure in each filter is made relatively small. do. In addition, the orifice 56 increases the differential pressure as the fluid flow rate passing through the orifice 56 increases, so it has the effect of averaging the amount of processing stock solution flowing into each series.

FIG. 6 shows the relationship between the flow rate and the differential pressure of each series when the differential pressure of the orifice is twice the differential pressure of the pipes and valves. As is clear from FIG. 6, the provision of the orifice 56 increases the differential pressure in the piping system, that is, the differential pressure between the piping, the valve, and the orifice, and the differential pressure in each filter becomes relatively small. Then, when the rated flow rate Q _NOR flows through each series, the differential pressure due to piping, valves, and orifices is ΔP ₃ , and the treated stock solution is supplied to each filter so that the total differential pressure in each series becomes ΔP ₄ . At this time, the flow rate of the A series having the filter with the shortest operating time is _Q2MAX , and the flow rate of the N series having the filter with the longest operating time is _Q2MIN . However, since the curve of differential pressure against flow rate is steeper than that of the conventional example shown in Figure 3, the difference between Q _2MAX and Q _2MIN is
It can be significantly smaller than the difference between Q _1MAX and Q _1MIN .

In pre-coat type filtration equipment for condensate in nuclear power plants, etc., the standard filtration rate is set to ensure filter performance, to be economical in operation, and to minimize the size of the filtration equipment. The differential pressure of the filter is generally approximately 8
m/H. The differential pressure between each filter is monitored by the differential pressure gauge 34 as described above, and it is desirable that the flow rate deviation between each filter is as small as possible. However, even if the filter is operated at a constant filtration speed, the time for the differential pressure to rise across the filter differs depending on the filter, and there is little need to manage the filtration speed through strict flow control using an equal flow rate control valve. ,
Fluctuations in filtration rate are allowed within a differential pressure range of ±1 m/H. That is, the differential pressure between the maximum flow rate filter and the minimum flow rate filter can be operated within a range of ±25% of the rated throughput. As in this embodiment shown in Fig. 6, when the differential pressure of the orifice is twice that of the piping/valve, the difference between the maximum flow rate filter and the minimum flow rate filter is ±20% of the rated throughput. This makes it possible to operate the filtration device without interfering with condensate treatment.

In addition, when a pump is installed in the upstream system of the inlet main pipe 12, such as the condensate system of a thermal power plant or nuclear power plant, the pump head is increased as the differential pressure of the filtration device increases, and the pump head is increased to increase the pump head to the downstream system. It is necessary to reduce the impact of However, the pumps used in these condensate systems are usually used for distances of 140 to 180 m.
Since it has a lifting head of about A _q , an increase in differential pressure of 10 to 20 mA _q due to a pipe loss generator such as an orifice is
It is 5 to 15% of the pump head, and the system around the pump,
There is no need to make changes to equipment design specifications. Therefore, flow control by providing the orifice 56 can eliminate the flow control valve and complicated flow control circuit without changing the fundamentals of the conventional system and equipment design, simplifying the structure of the filtration device and increasing its reliability. Improves sex. In addition, cost reduction and piping planning become easier.

FIG. 7 shows another embodiment of the filtration device according to the present invention. In this embodiment, the inlet branch pipe 12 is provided with a globe-type throttle valve 58 which can be used at an intermediate opening. In this case, unlike the case of the orifice 56 described above, the differential pressure can be adjusted.

In addition, when installing an orifice type flowmeter, it is also possible to provide the function of the above-mentioned pipe loss generating device by using a high differential pressure method with a general throttle ratio of β = 50 to 70% or more. . Further, in the above embodiments, a pre-coat type filtration device has been described, but the present invention can also be applied to a desalination device, a water purification device, an electromagnetic filter, etc.

〔Effect of the invention〕

As explained above, according to the present invention, a pipe loss generator is installed in the branch pipes of a plurality of filters having different operating times, which are arranged in parallel between the inlet main pipe and the outlet main pipe via the branch pipes. By providing this, the supply amount of the processing stock solution to each filter can be easily adjusted using the orifice 56 or the like, without requiring a complicated control circuit or the like as in the conventional case.
Can be easily adjusted.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of a conventional filtration device, Figure 2 is a diagram showing the relationship between processing time in the filter and filter differential pressure, and Figure 3 is for each series having filters with different processing flow rates and operating times. Figure 4 showing the relationship between
The figure shows a flow rate control system in a conventional filtration device, FIG. 5 is an explanatory diagram of an embodiment of a filtration device according to the present invention, and FIG. 6 shows a filter having a different processing flow rate and operating time from the above embodiment. FIG. 7, which is a diagram showing the relationship with the differential pressure for each series, is an explanatory diagram of another embodiment of the filtration device according to the present invention. 10...Inlet main pipe, 12...Inlet branch pipe, 20
A, 20B, 20N...filter, 28...outlet branch pipe, 30...outlet main pipe, 56...orifice,
58... Throttle valve.

Claims (1)

[Claims] 1. An inlet main pipe that guides the treatment stock solution, an outlet main pipe that collects the purified processing liquid, and liquid passage times that are arranged in parallel via a branch pipe between the inlet main pipe and the outlet main pipe, and In a filtration device comprising a plurality of filters, an inlet valve provided on the inlet main pipe side of the branch pipe from the filter, and an outlet valve provided on the outlet main pipe side of the branch pipe from the filter. . A filtration device, characterized in that each of the branch pipes is provided with a pipe line loss generator that independently increases the differential pressure as the fluid flow rate increases.