JPS6153116B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pure water producing apparatus in which a plurality of cation columns filled with a cation exchange resin and a plurality of anion columns filled with an anion exchange resin are connected alternately.

2. Description of the Related Art As a pure water producing apparatus using an ion exchange resin, a pure water producing apparatus in which a plurality of cation towers and anion towers are connected alternately is used. In such pure water production apparatuses, there are those that use a weakly basic anion exchange resin and those that use a strongly basic anion exchange resin in the first anion column. In this case, during regeneration, series regeneration is performed in which the regenerant is passed from the later column to the earlier column to increase the efficiency of use of the regenerant and to improve the quality of the final treated water.

Such pure water production equipment is generally designed to create a cation break (cations leak out before anions into the final treated water). The reason for this is that even if silica leaks in the case of an anion break, it cannot be checked with a conductivity meter, leading to a misunderstanding when the water sampling process has ended, and silica can cause hard scale if it enters the high-pressure boiler. This is because it is absolutely necessary to prevent leakage.

However, even in pure water production equipment designed to produce cation breaks, anion breaks sometimes occur due to fluctuations in water quality, resin deterioration, incomplete regeneration, and other reasons.

The present invention improves the above-mentioned drawbacks of conventional devices and provides a pure water production device that can determine the point of ion break even in the middle of the water sampling process and end the water sampling process before the anion break. The purpose is to

This invention provides a pure water production apparatus in which a plurality of cation columns filled with a cation exchange resin and a plurality of anion column exchange resins filled with an anion exchange resin are connected alternately, one column at a time. Detection means and PH at the outlet of the first anion column
This is a pure water production apparatus including a detection means and an arithmetic device that calculates the ion break point in the final treated water from the detected values obtained by these means.

The present invention will be described below with reference to embodiments shown in the drawings.
FIG. 1 is a system diagram of an embodiment implemented in a 4-bed, 5-column pure water production apparatus, and FIG. 2 is a block diagram of the control device.

In FIG. 1, 1 is a first cation column, 2 is a degassing column, 3 is a first anion column, 4 is a second cation column, and 5 is a second anion column, which are connected in series. A strongly acidic cation exchange resin bed is formed in the first cation column 1 and the second cation column 4, and a strongly basic anion exchange resin bed is formed in the first anion column 3 and the second anion column 5, respectively. ing.

Raw water enters the first cation tower 1 through pipe 6, is decationized there, enters the degassing tower 2 through pipe 7,
Gases such as carbon dioxide are removed here. The degassed water enters the first anion column 3 through a pipe 8 to be deanionized, and then passes through the pipe 9 to the second cation column 4 and then to the pipe 10.
The water then enters the second anion column 5 where it is decationized and deanionized, and flows out from the pipe 11 as final treated water (pure water).

In this embodiment, even if monovalent cations flow out from the first cation column 1, water continues to flow through the monovalent cations, and the second cation column 4 exchanges and adsorbs them. In this way, the first cation column 1
In the second cation column 4, mainly monovalent cations are exchanged and adsorbed. Normally, the water sampling process is terminated by a signal from the conductivity meter 12 when monovalent cations begin to leak out from the second cation column 4, but at this point, the first anion column 3 mainly collects monovalent or higher anions, In the anion column 5, monovalent anions and silica are mainly exchanged and adsorbed.

In the regeneration process, after flowing a regenerating agent (hydrochloric acid, sulfuric acid, etc.) from the pipe 13 into the second cation column 4 in a downward flow, the pipe 1
4 to the first cation column 1 in a downward flow to the pipe 15.
The regenerant (sodium hydroxide, etc.) is discharged from the pipe 16 to the second anion column 5 in a downward flow, and then discharged from the flow pipe 18 in a downward flow from the pipe 17 to the first anion column 3. playback. At this time, the regenerant is flowed in an amount corresponding to the total amount of resin in the first and second towers, but since all of the regenerant is flowed from the second tower, the second tower is completely regenerated, and even if the regeneration in the first tower is incomplete, the regenerant can be passed through. In the case of water, leaked ions are completely captured in the second column. In addition, if the adsorbed resin is directly regenerated with acid or alkali, the regeneration efficiency will be poor, but here the resin in the first column will exchange the monovalent ions desorbed from the second column with the ions that are divalent or more. If the monovalent ions are desorbed and then the monovalent ions are desorbed using an acid or alkali, the regeneration efficiency is extremely high.

In the present invention, the PH at the outlet of the first cation column and the PH at the outlet of the first anion column are measured, and from this the time point of ion break into the final treated water is calculated, thereby preventing anion break into the final treated water. is provided with a control device.

The control device includes the conductivity meter 12 that detects the conductivity of the treated water, the conductivity meter 19 that detects the conductivity of raw water, the PH meter 20 that detects the PH at the outlet of the first cation column 1, and the first anion Conductivity meter 21 that detects the conductivity at the outlet of the tower 3, PH at the outlet of the first anion tower
A PH meter 22 that detects the flow rate of raw water, a flow meter 23 that detects the flow rate of raw water, a flow meter 24 that detects the flow rate of treated water, a calculation device 25, an operator console 26, and an output device 27 are provided.
is composed of an input section 30, a calculation section 31, a storage section 32, and a control section 33.

In the above control device, the conductivity signal C ₁ of the conductivity meter 19, the PH signal P ₁ of the PH meter 20, the conductivity meter 21
conductivity signal C ₂ , PH signal P ₂ of PH meter 22 , conductivity signal C ₃ of conductivity meter 12 , flow rate signal of flow meter 23
F ₁ and the flow rate signal F ₂ from the flow meter 24 are sent to the input section 30 of the arithmetic unit 25 at regular intervals. Input section 3
At 0, each signal is A-D converted, and necessary input signals are selected and input to the calculation unit 31. Based on these signals, the calculation unit 31 performs internal calculations, and the results are output to the output device 27 and stored in the storage unit 32. These controls are performed by the control unit 33 in response to requests from the operator console 26 or in accordance with a program.

Next, the control mechanism will be explained according to the processing order. First, a cation break in the first cation column 1 or an anion break in the first anion column 3 is detected by the PH signals P ₁ and P ₂ from the PH meters 20 and 22, and the arithmetic unit 25 detects the final cation break leaving the second anion column 5. The point of ion break into the treated water is calculated,
The results are output to the output device 27.

That is, the PH signal P ₁ of the first cation column 1 before the cation break shows a low PH value, but when the cation break occurs, it shows a neutral PH value. Further, the PH signal P ₂ at the outlet of the first anion column 3 before the cation break in the first cation column 1 is high PH before the anion break in the second anion column 3 and low PH after the anion break. The PH signal P ₂ after the cation break in the first cation column 1 has a higher PH value before the anion break in the second anion column 3, and becomes neutral after the anion break. Therefore the PH signal P ₁ ,
Based on the change in P ₂ over time, the presence or absence of a break in the first cation column 1 and the first anion column 3 and the timing thereof are detected, and this is displayed on the output device 27.

Detection of break in each tower above is done by PH signal
Although this is possible based on P ₁ and P ₂ , in the embodiment, the conductivity signal C ₂ from the conductivity meter 21 is used to enable more accurate and quick determination. That is, a specific pattern appears in the conductivity change due to the difference in the break point of each tower, and by detecting this as the conductivity signal _C2 , the timing can be determined accurately and quickly.

When a break in the first cation column 1 and first anion column 3 is detected, it is possible to determine the point of ion break in the final treated water and whether the break is a cation break or an anion break based on the results and the design values of the entire device. The distinction and the amount of water that can be sampled thereafter are displayed on the output device 27. As a result, if an anion break occurs first in the final treated water, this cannot be checked by the conductivity meter 12, so the water sampling process is terminated based on the above calculation result.
This operation may be performed manually, but the output device 27
It is also possible to perform automatic control using commands. In addition, if cation break occurs first in the final treated water, the water sampling process may be terminated based on the calculation result.
More accurate control can be achieved using the conductivity signal _C3 .
In this case, the conductivity signal _C3 is input to the calculation device 25 to calculate the water quality, and a water quality transition curve is determined to determine the end point of the water sampling process.

Ion break into the final treated water can basically be determined from the PH signals P ₁ and P ₂ and the design value, but in order to make a more accurate judgment, it is necessary to check the conductivity of the conductivity meters 19 and 21. It is necessary to correct the design value using the signals C ₁ and C ₂ and the flow rate signal F ₁ or F ₂ from the flowmeters 23 and 24. That is, the ion break speed may be slow due to fluctuations in the quality of raw water, deterioration of the resin, quality of the previous regeneration, etc., but these can be accurately grasped by correcting the design values using the above-mentioned signals.

From the results of the above judgment of ion break to the treated water, the remaining exchange capacity of each tower at that point is calculated, and as a result, the amount of water that can be sampled thereafter is calculated, and the second cation column at the end of water sampling is calculated. The remaining exchange capacity of the fourth or second anion column 5 is also calculated. In a pure water production apparatus, it is desirable that a cation break occur immediately before an anion break occurs in the produced water, so that some residual cations remain in either the second cation column 4 or the second anion column 5 at the end of the water sampling process. If there is replacement capacity, it is desirable to change the next playback level. The appropriate amount of regenerant for the next regeneration can be calculated from the remaining exchange capacity and the design value, but in this case, it can also be calculated from the conductivity signals C ₁ , C ₂ , C ₃ and the flow rate signals F ₁ , F _{2 .} By making corrections, more accurate values can be obtained.

The above control device also functions effectively in the regeneration process. The regeneration process is as described above, but in the latter half of this regeneration process, cleaning is performed by circulating the wash water in the same order as in the normal water sampling process. In this case, the conductivity signal _C3 is input to a calculation device to calculate the water quality, and a water quality transition curve is determined to determine the regeneration end point. In connection with this, by inputting the flow rate signal _F1 or _F2 , the amount of water used in the regeneration process is checked and the quality of the regeneration is determined.

Although the above embodiments relate to a 4-column, 5-bed pure water production apparatus, the number of cation towers and anion towers is not limited as long as they are plural, and the degassing tower 2 is not necessarily Not necessary. Furthermore, even when the first anion column is filled with a weakly basic anion exchange resin, almost the same control can be achieved. The reproduction method can also be applied to cases other than series reproduction.

As described above, according to the present invention, it is possible to determine whether there is an ion break in the treated water during the water sampling process, and the water sampling process can be completed before an anion break occurs. In addition, it is possible to calculate the amount of water that can be sampled afterward during the water sampling process, and it is also possible to calculate the appropriate amount of regenerant for the next regeneration process, which allows for pure water production without wasting regenerant. It can be carried out.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of an embodiment, and FIG. 2 is a block diagram of a control device, in which 1 is a first cation column, 2 is a degassing column, 3 is a first anion column, 4 is a second cation column, 5 is the second anion tower, 12, 19, 21 are conductivity meters, 20, 22 are PH meters, 23, 24 are flow meters, 25 is an arithmetic unit, 26 is an operator console, 27 is an output device, 30 is an input section , 31 is an arithmetic unit, 32 is a storage unit, and 33 is a control unit.

Claims (1)

[Claims] 1. In a pure water production apparatus in which a plurality of cation towers filled with a cation exchange resin and a plurality of anion towers filled with an anion exchange resin are connected alternately, one tower at a time, a PH detection means at the outlet of the first cation tower; A pure water production apparatus including a PH detection means at the outlet of a first anion column, and a calculation device that calculates an ion break point in final treated water from the detected values obtained by these means.